MODEL CONTEXT PROTOCOL

Japanese Law MCP

TaiLexi AI’s Japanese Law MCP is a Model Context Protocol server that lets AI assistants such as Claude and ChatGPT search Japanese law directly: 67,464 court decisions from the Supreme Court, High Courts, District Courts, the IP High Court and others, plus 125,072 official records — tax litigation reports, Shōmu Geppō, National Tax Tribunal rulings, Labour Commission orders, JFTC and JPO decisions and more (192,536 in all); 8,984 current statutes from e-Gov (243,568 articles) with amendment history; and 71,119 pieces of agency guidance.

Endpoint: https://jp.tailexi.org/mcp
Transport: Streamable HTTP (stateless, JSON responses)
Authentication: None
Rate limits: Rate limits apply
Tools: 11, all read-only

01Overview

With these tools an AI assistant can do the following. Answers can carry the court, date, case number, law report and a source URL, so every decision it cites can be checked.

Find casesSearch by keyword, case number, citation (最大判昭和48年4月4日, 民集67巻6号1320頁) or article (民法709条). Leading precedents rank first.

Read a decisionPoints decided (判示事項), summary of holdings (裁判要旨), statutes referred to, the court below and the full text. Long texts come in chunks; heading offsets let you read only the part you need.

Trace citationsThe Supreme Court precedents a decision cites, and the later decisions that cite them — a precedent’s weight, in numbers.

Survey an issueCount the decisions on an issue, see how they spread across courts, decades and outcomes, and find the most-cited articles and leading precedents — in one call.

Check the statuteFetch the current text of an article, paragraphs and items included, with the number of decisions citing it and the leading ones.

Locate a provisionFind the statute and article from a law’s name, its abbreviation or the words it uses.

02Quickstart

Add the endpoint to your client
Add https://jp.tailexi.org/mcp to your AI client (see Client setup). No API key or account needed.
Ask your question
Ask in English or Japanese — there is no need to name the tools; the assistant chooses them. The data itself is in Japanese, so including the Japanese legal term sharpens the search.
Check the sources
The URLs in each answer open the full decision, the original PDF or the statute page.

Example prompts

How does the Supreme Court decide whether a defendant had good reason to believe a defamatory statement was true (真実相当性)? Cite the leading cases.

List five leading Supreme Court decisions on causation under Article 709 of the Civil Code, with citations.

What were the points decided in 最大決平成25年9月4日, and how has it been cited since?

Summarize the trend in cases on the employer’s duty of care for safety (安全配慮義務) and overwork, with the articles cited most often.

A typical sequence

search_judgmentsFind candidate cases

→

get_judgmentRead the holdings and text

→

get_cited_byCheck later citations

→

get_law_articleCheck the statutory wording

03Client setup

Any MCP client that supports Streamable HTTP connects with nothing more than the endpoint URL.

Claude on the web and the desktop app share the same Connectors settings.

Open Settings › Connectors.
Choose Add custom connector, enter TaiLexi AI Japan Law as the name and https://jp.tailexi.org/mcp as the URL, then add it.
Enable “TaiLexi AI Japan Law” in the chat’s tools menu and start asking.

Custom connectors may not be available on every plan.

Under Settings › Apps & Connectors › Advanced settings, turn on Developer mode.
Click Create to add a connector, enter https://jp.tailexi.org/mcp as the MCP server URL and set authentication to None.
Select the connector in a chat, then ask.

ChatGPT’s menus and labels vary by plan and over time.

Terminal

# This project only
claude mcp add --transport http tailexi-jp https://jp.tailexi.org/mcp

# All projects
claude mcp add --transport http --scope user tailexi-jp https://jp.tailexi.org/mcp

Add to ~/.cursor/mcp.json (global) or to .cursor/mcp.json in your project.

mcp.json

{
  "mcpServers": {
    "tailexi-jp": {
      "url": "https://jp.tailexi.org/mcp"
    }
  }
}

Create .vscode/mcp.json at the project root (used by GitHub Copilot’s agent mode).

.vscode/mcp.json

{
  "servers": {
    "tailexi-jp": {
      "type": "http",
      "url": "https://jp.tailexi.org/mcp"
    }
  }
}

Add to ~/.gemini/settings.json.

settings.json

{
  "mcpServers": {
    "tailexi-jp": {
      "httpUrl": "https://jp.tailexi.org/mcp"
    }
  }
}

Clients without remote MCP support (local stdio only) can bridge through mcp-remote (requires Node.js).

Config file

{
  "mcpServers": {
    "tailexi-jp": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://jp.tailexi.org/mcp"
      ]
    }
  }
}

04Use from an API or SDK

To build it into an application, use your model provider’s remote MCP support or the official MCP SDKs.

Pass the server as a remote MCP tool and the model calls its tools as needed.

pip install openai

from openai import OpenAI

client = OpenAI()
response = client.responses.create(
    model="gpt-5",  # a model that supports MCP tools
    tools=[{
        "type": "mcp",
        "server_label": "tailexi_jp",
        "server_url": "https://jp.tailexi.org/mcp",
        "require_approval": "never",
    }],
    input="最大決平成25年9月4日の判示事項と、その後の引用状況を教えてください。",
)
print(response.output_text)

The MCP connector (beta) lets the Messages API connect to remote MCP servers. See Anthropic’s documentation for the current beta name and parameters.

pip install anthropic

import anthropic

client = anthropic.Anthropic()
response = client.beta.messages.create(
    model="claude-sonnet-5-5",
    max_tokens=2000,
    messages=[{"role": "user", "content": "民法709条の因果関係に関する主要な最高裁判例を、引用形式つきで挙げてください。"}],
    mcp_servers=[{"type": "url", "url": "https://jp.tailexi.org/mcp", "name": "tailexi-jp"}],
    betas=["mcp-client-2025-04-04"],
)
print(response.content)

pip install mcp

import asyncio
from mcp import ClientSession
from mcp.client.streamable_http import streamablehttp_client

async def main():
    async with streamablehttp_client("https://jp.tailexi.org/mcp") as (read, write, _):
        async with ClientSession(read, write) as session:
            await session.initialize()
            result = await session.call_tool(
                "search_judgments",
                {"query": "名誉毀損 公共の利害", "court_level": ["最高裁"], "limit": 5},
            )
            print(result.content[0].text)

asyncio.run(main())

npm install @modelcontextprotocol/sdk

import { Client } from "@modelcontextprotocol/sdk/client/index.js";
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";

const client = new Client({ name: "my-app", version: "1.0.0" });
await client.connect(new StreamableHTTPClientTransport(new URL("https://jp.tailexi.org/mcp")));

const result = await client.callTool({
  name: "get_law_article",
  arguments: { law: "民法", articles: ["709", "710"] },
});
console.log(result.content[0].text);

05Tools

Tool	Purpose
`search_judgments`	Search case law (case numbers, citations and articles accepted as-is)
`get_judgment`	One decision in detail (points decided, summary, text, Supreme Court precedents cited)
`get_cited_by`	Later decisions citing a Supreme Court precedent
`get_commentary`	Journal case notes and commentaries on a decision, with citations
`analyze_issue`	Survey an issue (distribution, most-cited articles, leading precedents)
`get_law_article`	Fetch articles (several at once, with citing-case counts)
`search_laws`	Find statutes and articles by name or wording
`search_guidance`	Search guidance (articles and circular numbers accepted as-is)
`get_guidance`	Full text of one guidance document (with the articles it interprets)
`get_legislative_history`	Legislative history of an article (Diet answers, reasons, resolutions) or of a statute
`search_diet_records`	Search Diet remarks made in bill deliberations

Tools return a JSON string (no whitespace; empty fields omitted). To save tokens on the model side, full texts are fetched only when needed.

TOOL 01`search_judgments`Search case lawRead-only

Full-text search over Japanese case law. Results are ranked by relevance × importance by default, so Supreme Court decisions, reported cases and frequently cited ones come first. Case numbers, citations or articles written in query become filters automatically.

Parameters

Parameter	Type	Default	Description
`query`	string	""	Search terms. Space = AND, `A OR B`, `-term` = exclude, `"…"` = phrase. Case numbers, citations and articles also work. Traditional Chinese characters are mapped to their Japanese forms.
`court_level`	string[]	—	`最高裁`Supreme Court `高裁`High Court `知財高裁`IP High Court `地裁`District Court `家裁`Family Court `簡裁`Summary Court
`kind`	string[]	—	`民事`civil `刑事`criminal `行政`administrative `租税`tax `労働`labor `知的財産`IP `独禁`antitrust `金融`financial `情報公開`information disclosure `家事`family `社会保障`social security `消費者`consumer `海事`maritime `環境`environment / pollution
`reporter`	string[]	—	`民集`Minshū, civil reports `刑集`Keishū, criminal reports `集民`Shūmin, civil collection `集刑`Shūkei, criminal collection `その他`other (高民集, 行集, etc.)
`cite_law`	string	—	Restrict to decisions that refer to or cite this statute (name or abbreviation). Use with `cite_article`.
`cite_article`	string	—	Article number, e.g. `709`, `3の2` or `第七百九条`.
`year_from / year_to`	integer	—	Range of decision years (Gregorian calendar).
`grand_bench_only`	boolean	false	Only Supreme Court Grand Bench decisions.
`source`	string[]	—	Filter by source: `courts`Courts in Japan website `nta`tax litigation reports `kfs`National Tax Tribunal rulings `churoi`Labour Commission orders and cases `shomu`Shōmu Geppō `jftc`JFTC decisions `jftc_orders`cease-and-desist orders, etc. `fsa_shinpan`FSA surcharge hearings `jyouhou_toushin`Information Disclosure and Personal Information Protection Review Board reports `soumu_fufuku`administrative appeal rulings `rouhoken_shinsa`Labour Insurance Appeal Committee rulings `shaho_shinsa`Social Insurance Appeal Committee rulings `caa_orders`Premiums and Representations Act orders `kainan`Japan Marine Accident Tribunal rulings `kouchoi`Environmental Dispute Coordination Commission rulings `genbai`Nuclear Damage Compensation ADR settlements `sesc`SESC recommendations `jpo_shinketsu`JPO trial decisions
`sort`	string	"relevance"	`relevance`relevance × importance `newest`newest first `oldest`oldest first `most_cited`most cited first
`doc_type`	string	"all"	`all` = court decisions and administrative rulings (courts ranked first); `court` = court decisions only; `admin` = administrative rulings, reports, orders and decisions only.
`exact_terms`	boolean	false	When true, synonyms and spelling variants (listed in `notes`) are not added; only the words you typed are searched. Quoting a word with `"…"` does the same for that word.
`detail`	string	"auto"	How much each result carries. `auto` = `full` when `limit` ≤ 5, `compact` when it is 6 or more; `compact` = only the first 120 characters of the points decided (or the summary), one matching passage for records with neither, and up to four referenced articles; `full` = points decided and summary (300 characters each) plus every matching passage. Ten results shrink from about 7,700 to about 4,100 characters.
`page / limit`	integer	1 / 10	Page (up to 50) and results per page (up to 20).

Returns

Field	Description
`total / page / pages / has_more`	Total hits and paging — the same shape for every list tool; an out-of-range page returns `results: []`.
`detail`	The level of detail returned (`compact` or `full`).
`notes`	How the query was read (parts recognized as a citation, case number or article, synonyms added, and so on) — an array of strings.
`results[].citation`	Standard citation, e.g. `最一小判昭和41年6月23日民集20巻5号1118頁`
`results[].gist / summary`	Opening of the points decided and the summary of holdings (where published).
`results[].match_excerpts`	Matching passages from the text, with hits marked 【like this】.
`results[].cited_by`	Number of decisions in the collection that cite this one (Supreme Court precedents).
`results[].commentary_count`	Number of journal articles (case notes, commentaries, etc.) on this decision (see get_commentary).
`results[].url`	Decision page, with links to the full text and the original PDF.

Example

Call (arguments)

{
  "query": "名誉毀損 公共の利害",
  "court_level": [
    "最高裁"
  ],
  "limit": 3
}

Response (example, abridged)

{
  "total": 25,
  "page": 1,
  "pages": 9,
  "detail": "full",
  "notes": ["「名誉毀損」に加えて 名誉き損 も検索（exact_terms=true で止める）。", "内訳：裁判所の裁判 25 件・行政機関の裁決・答申等 0 件。"],
  "results": [
    {
      "id": "51844",
      "citation": "最一小判昭和56年4月16日刑集35巻3号84頁",
      "court": "最高裁判所第一小法廷",
      "date": "1981-04-16",
      "date_wareki": "昭和56年4月16日",
      "type": "判決",
      "case_no": "昭和55年(あ)第273号",
      "case_name": "名誉毀損",
      "result": "破棄差戻",
      "reporter": "刑集35巻3号84頁",
      "kind": ["刑事"],
      "cited_by": 7,
      "commentary_count": 10,
      "url": "https://jp.tailexi.org/hanrei/51844",
      "gist": "一　私人の私生活上の行状と刑法二三〇条の二項一項にいう「公共ノ利害ニ関スル事実」\n\n二　刑法二三〇条の二第一項にいう「公共ノ利害ニ関スル事実」にあたるとされた事例\n\n三　刑法二三〇条の二第一項にいう…",
      "summary": "一　私人の私生活上の行状であつても、そのたずさわる社会的活動の性質及びこれを通じて社会に及ぼす影響力の程度などのいかんによつては、その社会的活動に対する批判ないし評価の一資料として、刑法二三〇条の二…",
      "match_excerpts": [
        "そうして、原審弁護人が、「被告人は、宗教界の刷新という公益目的のもとに【公共の利害】に関する事実を公表したものであるから、事実の真実性の立証を許さないまま【名誉毀損】罪の成立を認めた第一審判決は審理不尽である。」"
      ],
      "refs": ["刑法230条の2"]
    },
    {
      "id": "52665",
      "citation": "最大判昭和61年6月11日民集40巻4号872頁",
      "court": "最高裁判所大法廷",
      "date": "1986-06-11",
      "date_wareki": "昭和61年6月11日",
      "type": "判決",
      "case_no": "昭和56年(オ)第609号",
      "case_name": "損害賠償",
      "result": "棄却",
      "reporter": "民集40巻4号872頁",
      "kind": ["民事"],
      "cited_by": 66,
      "commentary_count": 15,
      "url": "https://jp.tailexi.org/hanrei/52665",
      "gist": "一　出版物の印刷、製本、販売、頒布等の仮処分による事前差止めと憲法二一条二項前段にいう検閲\n二　名誉侵害と侵害行為の差止請求権\n三　公務員又は公職選挙の候補者に対する評価、批判等に関する出版物の印刷…",
      "summary": "一　雑誌その他の出版物の印刷、製本、販売、頒布等の仮処分による事前差止めは、憲法二一条二項前段にいう検閲に当たらない。\n二　名誉侵害の被害者は、人格権としての名誉権に基づき、加害者に対して、現に行わ…",
      "match_excerpts": [
        "昭和四一年六月二三日第一小法廷判決は、「民法上の不法行為たる【名誉毀損】については、その行為が【公共の利害】に関する事実に係りもつぱら公益を図る目的に出た場合には、摘示された事実が真実であることが証明されたときは、右行為には違法性"
      ],
      "refs": [
        "日本国憲法13条",
        "日本国憲法21条",
        "民事訴訟法757条",
        "民事訴訟法760条",
        "民法1条の2",
        "民法198条"
      ]
    },
    "…"
  ]
}

Pass a citation as-is and the decision is identified by court, date and law report.

Call (arguments)

{
  "query": "最大判昭和48年4月4日"
}

Response (example, abridged)

{
  "total": 3,
  "notes": ["判例の引用として解釈：最高裁判所大法廷・1973-04-04"],
  "results": [
    {
      "id": "51807",
      "citation": "最大判昭和48年4月4日刑集27巻3号265頁",
      "court": "最高裁判所大法廷",
      "date": "1973-04-04",
      "date_wareki": "昭和48年4月4日",
      "type": "判決",
      "case_no": "昭和45年(あ)第1310号",
      "case_name": "尊属殺人",
      "result": "破棄自判",
      "reporter": "刑集27巻3号265頁",
      "kind": ["刑事"],
      "cited_by": 39,
      "url": "https://jp.tailexi.org/hanrei/51807",
      "gist": "刑法二〇〇条と憲法一四条一項",
      "summary": "刑法二〇〇条は、憲法一四条一項に違反する。",
      "refs": ["日本国憲法14条", "…"]
    }
  ]
}

TOOL 02`get_judgment`Read a decisionRead-only

Returns one decision in detail, with three citation styles: standard, short and judgment style. The text comes max_chars characters at a time; fetch the rest with next_offset. sections gives the offsets of headings such as 主文 (operative part) and 理由 (reasons), so you can read only what you need.

Parameters

Parameter	Type	Default	Description
`id`	string	—	Decision ID (the `id` from `search_judgments`). Give this or `case_no`.
`case_no`	string	—	Case number. Unique at the Supreme Court; lower-court numbers repeat across courts, so give `court` as well.
`court`	string	—	Court name, when using `case_no` for a lower-court decision.
`headnotes_only`	boolean	false	Omit the text; return only the points decided, summary, statutes referred to and citations.
`max_chars`	integer	12000	Maximum characters of text (1,000–40,000).
`offset`	integer	0	Where in the text to start.

Returns

Field	Description
`citation / citation_short / citation_judgment_style`	The three citation styles. Judgment style looks like `最高裁平成24年(ク)第984号同25年9月4日大法廷決定・民集67巻6号1320頁`.
`gist / summary / ref_law`	Points decided, summary of holdings and statutes referred to, as published by the court.
`lower_court`	Court, case number and date of the decision below.
`cites_precedents`	Supreme Court precedents cited in the text. If `in_database` is true, fetch them by `id`.
`cited_by_count`	Number of decisions in the collection that cite this one (Supreme Court only).
`commentary / commentary_total`	The first five case notes and related articles (same shape as get_commentary) and the total; `commentary_attribution` is the attribution (NDL Japanese Periodicals Index, CC BY 4.0).
`text_status / alt_id_with_text`	When there is no text: why (`本文補完中` = being extracted from the PDF, `本文未掲載・原本PDFのみ` = PDF only, `概要のみ公表` = summary only, etc.), and the `id` of another record of the same case and date that has the text.
`sections / text / truncated / next_offset`	Heading offsets, the text, whether more follows, and where to resume.
`pdf_url / source_url`	The source’s original PDF and web page (Courts in Japan website and others).
`source / attribution`	The source (Courts in Japan website, tax litigation reports, etc.) and the attribution to include when quoting.
`full_text_withheld`	When the text is withheld because it may contain personal names, the reason (text and sections are omitted).

Example

Call (arguments)

{
  "id": "83520",
  "max_chars": 1500
}

Response (example, abridged)

{
  "id": "83520",
  "citation": "最大決平成25年9月4日民集67巻6号1320頁",
  "citation_short": "最大決平25・9・4民集67巻6号1320頁",
  "citation_judgment_style": "最高裁平成24年(ク)第984号同25年9月4日大法廷決定・民集67巻6号1320頁",
  "court": "最高裁判所大法廷",
  "date": "2013-09-04",
  "date_wareki": "平成25年9月4日",
  "type": "決定",
  "result": "破棄差戻",
  "case_no": "平成24年(ク)第984号",
  "case_name": "遺産分割審判に対する抗告棄却決定に対する特別抗告事件",
  "reporter": "民集67巻6号1320頁",
  "kind": ["民事"],
  "lower_court": {
    "court": "東京高等裁判所",
    "case_no": "平成24年(ラ)第955号",
    "date": "2012-06-22"
  },
  "gist": "１　民法９００条４号ただし書前段の規定と憲法１４条１項\n２　民法９００条４号ただし書前段の規定を違憲とする最高裁判所の判断が他の相続における上記規定を前提とした法律関係に及ぼす影響",
  "summary": "１　民法９００条４号ただし書前段の規定は，遅くとも平成１３年７月当時において，憲法１４条１項に違反していた。\n２　民法９００条４号ただし書前段の規定が遅くとも平成１３年７月当時において憲法１４条１項に違反していたとする最高裁判所の判断は，上…",
  "ref_law": "（１，２につき）憲法14条1項，民法900条　（２につき）憲法81条",
  "cites_precedents": [
    {
      "id": "53094",
      "citation": "最三小判昭和39年5月27日民集18巻4号711頁",
      "in_database": true
    },
    {
      "id": "51807",
      "citation": "最大判昭和48年4月4日刑集27巻3号265頁",
      "in_database": true
    },
    {
      "id": "55859",
      "citation": "最大決平成7年7月5日民集49巻7号1789頁",
      "in_database": true
    }
  ],
  "cited_by_count": 15,
  "url": "https://jp.tailexi.org/hanrei/83520",
  "pdf_url": "https://www.courts.go.jp/assets/hanrei/hanrei-pdf-83520.pdf",
  "source_url": "https://www.courts.go.jp/hanrei/83520/detail2/index.html",
  "sections": [
    {
      "label": "主文",
      "offset": 61
    },
    {
      "label": "理由",
      "offset": 91
    }
  ],
  "text": "平成２４年（ク）第９８４号，第９８５号遺産分割審判に対する抗告棄却決定に対する特別抗告事件\n平成２５年９月４日大法廷決定\n主文\n原決定を破棄する。\n本件を東京高等裁判所に差し戻す。\n理由\n抗告人Ｙ１の抗告理由第１及び抗告人Ｙ２の代理人小田原…",
  "chars_total": 14967,
  "offset": 0,
  "truncated": true,
  "next_offset": 1500
}

TOOL 03`get_cited_by`Citing decisionsRead-only

Lists the later decisions that cite a Supreme Court precedent. Citations are identified from case numbers in the text, or from references to the date, bench and law report. Supreme Court decisions come first, then reported cases, then by citation count. Each result’s citing_context is the sentence that cites the precedent (the citation itself in 【】), showing on which point it was cited.

Parameters

Parameter	Type	Default	Description
`id`required	string	—	ID of the Supreme Court precedent.
`page / limit`	integer	1 / 10	Page (up to 50) and results per page (up to 20).

Example

Call (arguments)

{
  "id": "83520",
  "limit": 3
}

Response (example, abridged)

{
  "precedent": "最大決平成25年9月4日民集67巻6号1320頁",
  "total": 17,
  "page": 1,
  "results": [
    {
      "id": "85547",
      "citation": "最大判平成27年12月16日民集69巻8号2427頁",
      "court": "最高裁判所大法廷",
      "date": "2015-12-16",
      "date_wareki": "平成27年12月16日",
      "type": "判決",
      "case_no": "平成25年(オ)第1079号",
      "case_name": "損害賠償請求事件",
      "result": "棄却",
      "reporter": "民集69巻8号2427頁",
      "cited_by": 75,
      "url": "https://jp.tailexi.org/hanrei/85547",
      "citing_context": "…性等を審査する際に，採用した手段自体の実質的な相当性の有無の判断をも行う必要があるのであれば，合憲性審査においては，平成２５年の嫡出でない子の相続分に関する最高裁大法廷の違憲決定（【最高裁平成２４年（ク）第９８４号，第９８５号同２５年９月４日大法廷決定・民集６７巻６号１３２０頁】）が説示したように，最初から，女性に対してのみ再…"
    },
    {
      "id": "85494",
      "citation": "最大判平成27年11月25日民集69巻7号2035頁",
      "court": "最高裁判所大法廷",
      "date": "2015-11-25",
      "date_wareki": "平成27年11月25日",
      "type": "判決",
      "case_no": "平成27年(行ツ)第253号",
      "case_name": "選挙無効請求事件",
      "result": "棄却",
      "reporter": "民集69巻7号2035頁",
      "cited_by": 60,
      "url": "https://jp.tailexi.org/hanrei/85494",
      "citing_context": "…対し，いわゆる事情判決の法理は，行政事件訴訟法の規定に含まれる法の一般原則に基づくものと理解されているが，これはまた違憲判決の効果の範囲・内容を定めるについて裁判所の有する裁量権（【最高裁平成２４年（ク）第９８４号，第９８５号同２５年９月４日大法廷決定・民集６７巻６号１３２０頁参照】）の表れの一つでもある。"
    },
    "…"
  ]
}

TOOL 04`get_commentary`Case notes and literatureRead-only

Returns bibliographic data for journal articles about one decision — official commentaries, case notes, digests and related articles — from the National Diet Library’s 雑誌記事索引 (Japanese Periodicals Index, CC BY 4.0); the articles’ text is not included. Each citation follows Japanese legal citation style (宮沢俊義「三菱樹脂事件について」ジュリ553号42頁（1974年）), with the first page of the article. Serially numbered journals (判例時報, 判例タイムズ, ジュリスト, 法学教室 and the like) are cited by abbreviated title and serial number (判タ1181号116頁) when the record has the serial number, otherwise by full title, volume and issue; unsigned research-judge commentaries are marked “（調査官解説）”. Pages and volume numbers missing from the data are never filled in. Articles are matched to decisions by rule (no AI) from the court, date, case number or popular case name in the article title, and may be wrong. Books and law-report commentaries are not covered.

Parameters

Parameter	Type	Default	Description
`id`required	string	—	Decision ID (the `id` from `search_judgments` or `get_judgment`).
`limit`	integer	20	Number of results (up to 50).
`offset`	integer	0	Where to start. When `has_more` is true, pass `next_offset` to continue.

Returns

Field	Description
`total / by_kind / offset / limit / page / pages / next_offset / has_more`	Total, counts by kind, and paging (the shared shape for offset-based tools).
`results[].kind`	`調査官解説`official commentary by Supreme Court research judges (e.g. 時の判例) `百選`Hyakusen casebooks (別冊ジュリスト; edition in `hyakusen`) `評釈`case note `紹介`digest `関連`related article (in this order, oldest first within each kind).
`results[].citation`	Japanese legal citation: author 「title」 journal volume/issue page (year).
`results[].authors / title / journal / number / pages / year`	Each bibliographic field (journal without parallel title or publisher; pages is the article’s page range).
`results[].url`	The NDL Search record.
`attribution / matching_note`	The attribution to include when quoting, and a note that the matching is automatic.

Example

Call (arguments)

{
  "id": "51931",
  "limit": 3
}

Response (example, abridged)

{
  "judgment": "最大判昭和48年12月12日民集27巻11号1536頁",
  "id": "51931",
  "total": 16,
  "by_kind": {
    "百選": 1,
    "評釈": 9,
    "紹介": 1,
    "関連": 5
  },
  "offset": 0,
  "limit": 3,
  "page": 1,
  "pages": 6,
  "next_offset": 3,
  "matching_note": "判決との対応は、記事名に書かれた裁判所・裁判年月日・事件番号・事件の通称などから機械的に付けたもので、誤りを含むことがあります。",
  "attribution": "出典：国立国会図書館雑誌記事索引（CC BY 4.0）",
  "has_more": true,
  "results": [
    {
      "kind": "百選",
      "hyakusen": "憲法判例百選Ⅰ〔第8版〕",
      "citation": "西村枝美「私法関係と基本的人権 : 三菱樹脂事件[最高裁昭和48.12.12大法廷判決]」憲法判例百選Ⅰ〔第8版〕（別冊ジュリスト273号）20頁（2025年）",
      "authors": ["西村枝美"],
      "title": "私法関係と基本的人権 : 三菱樹脂事件[最高裁昭和48.12.12大法廷判決]",
      "journal": "憲法判例百選Ⅰ〔第8版〕",
      "number": "（別冊ジュリスト273号）",
      "pages": "20-21",
      "year": 2025,
      "url": "https://ndlsearch.ndl.go.jp/books/R000000004-I034360160"
    },
    {
      "kind": "評釈",
      "citation": "宮沢俊義「三菱樹脂事件について」ジュリ553号42頁（1974年）",
      "authors": ["宮沢俊義"],
      "title": "三菱樹脂事件について",
      "journal": "ジュリスト",
      "number": "553号",
      "pages": "42-43",
      "year": 1974,
      "url": "https://ndlsearch.ndl.go.jp/books/R000000004-I412700"
    },
    {
      "kind": "評釈",
      "citation": "「三菱樹脂事件判決の意義と問題点(特集)」法律のひろば27巻3号4頁（1974年）",
      "title": "三菱樹脂事件判決の意義と問題点(特集)",
      "journal": "法律のひろば",
      "number": "27巻3号",
      "pages": "4-36",
      "year": 1974,
      "url": "https://ndlsearch.ndl.go.jp/books/R000000004-I416063"
    }
  ]
}

TOOL 05`analyze_issue`Survey an issueRead-only

Aggregates every decision that matches an issue (a set of search conditions) — the tool for “what is the trend in practice?” and “what is the leading case?”. Leading precedents (leading_precedents) put first the Supreme Court decisions that the matching decisions cite near the issue’s terms (within 600 characters; cited_near_terms), with cited_in_results counting citations anywhere in the text — so that a precedent cited for a different point in the same judgment (e.g. a remedial-order case cited by a probation-dismissal judgment) does not lead. Unless the issue is labour-union law (unfair labour practices, remedial orders and the like), precedents cited by the Labour Relations Commission court-case collection are listed separately in leading_precedents_labor_commission. Articles cited by routine rather than on the issue — costs, provisional execution, dismissal of appeals, sentencing arithmetic, the legal basis of a ruling — are listed separately in procedural_articles and kept out of most_cited_articles, which lists articles cited by at least two decisions (when fewer than five decisions match, articles cited only once are included and notes says so). Top results are split into court decisions (top_judgments) and agency rulings and reports (top_admin_decisions).

Parameters

query court_level kind cite_law cite_article year_from year_to — same meaning as in search_judgments.

Example

Call (arguments)

{
  "query": "安全配慮義務 過労"
}

Response (example, abridged)

{
  "total": 113,
  "by_court_level": {
    "地裁": 87,
    "高裁": 20,
    "最高裁": 5,
    "知財高裁": 1
  },
  "by_kind": {
    "民事": 97,
    "労働": 34,
    "行政": 15,
    "知的財産": 2
  },
  "by_result": {
    "棄却": 9,
    "破棄自判": 4,
    "一部破棄差戻": 2,
    "破棄差戻": 2,
    "原判決取消": 1,
    "原判決変更": 1,
    "不明・その他": 94
  },
  "by_decade": {
    "1980年代": 3,
    "1990年代": 8,
    "2000年代": 37,
    "2010年代": 32,
    "2020年代": 33
  },
  "notes": [
    "by_court_level・by_result・by_decade は合計が total になる（不明・その他＝記載なし・少数の区分）。by_kind は 1 件が複数の分野に属しうるため合計は total を超えることがある。",
    "集計は裁判所の裁判 113 件。同じ条件の行政機関の裁決・答申・命令等が別に 16 件ある（doc_type=admin／all で集計、上位 3 件は top_admin_decisions）。",
    "「安全配慮義務」に加えて 健康配慮義務・心身の健康を損なうことがないよう注意する義務 も集計に含めた（exact_terms=true で止める）。",
    "「過労」に加えて 過重な業務・過重業務・業務の過重性・過重負荷・業務の負担が過重 も集計に含めた（exact_terms=true で止める）。",
    "leading_precedents は、論点の語の近く（前後 600 字）で引用されている最高裁判例を上位にした（cited_near_terms）。cited_in_results は該当する判例のうちその先例を引用する数（本文のどこでの引用かを問わない）。"
  ],
  "most_cited_articles": [
    {
      "article": "国家賠償法1条",
      "judgments": 24
    },
    {
      "article": "民法715条",
      "judgments": 23
    },
    {
      "article": "民法709条",
      "judgments": 20
    },
    {
      "article": "民法415条",
      "judgments": 18
    }
  ],
  "procedural_articles": [
    {
      "article": "民事訴訟法61条",
      "judgments": 11
    },
    {
      "article": "民事訴訟法89条",
      "judgments": 7
    },
    {
      "article": "行政事件訴訟法7条",
      "judgments": 6
    }
  ],
  "leading_precedents": [
    {
      "id": "52222",
      "citation": "最二小判平成12年3月24日民集54巻3号1155頁",
      "gist": "一　長時間にわたる残業を恒常的に伴う業務に従事していた労働者がうつ病にり患し自殺した場合に使用者の民法七一五条に基づく損害賠償責任が肯定された事例\n二　業務の負担が過重であることを原因として心身に生じた損害につき労働者がする不法行為に基づく賠償請求において使用者の賠償額を決定するに当たり右労働者の性格及びこれに基づく業",
      "cited_in_results": 33,
      "cited_near_terms": 29,
      "url": "https://jp.tailexi.org/hanrei/52222"
    },
    {
      "id": "52180",
      "citation": "最三小判昭和59年4月10日民集38巻6号557頁",
      "gist": "宿直勤務中の従業員が盗賊に殺害された事故につき会社に安全配慮義務の違背に基づく損害賠償責任があるとされた事例",
      "cited_in_results": 8,
      "cited_near_terms": 8,
      "url": "https://jp.tailexi.org/hanrei/52180"
    }
  ],
  "top_judgments": [
    {
      "id": "93868",
      "citation": "最二小判令和7年3月7日民集79巻3号1159頁",
      "court": "最高裁判所第二小法廷",
      "date": "2025-03-07",
      "date_wareki": "令和7年3月7日",
      "type": "判決",
      "case_no": "令和5年(受)第927号",
      "case_name": "損害賠償請求事件",
      "result": "破棄差戻",
      "reporter": "民集79巻3号1159頁",
      "cited_by": 1,
      "url": "https://jp.tailexi.org/hanrei/93868"
    }
  ],
  "top_admin_decisions": [
    {
      "id": "jyouhoutoushin-H29-gj-407",
      "citation": "情報公開・個人情報保護審査会平成30年1月12日答申（平成29年度（行情）答申第407号）",
      "court": "総務省（情報公開・個人情報保護審査会）",
      "date": "2018-01-12",
      "date_wareki": "平成30年1月12日",
      "type": "答申",
      "case_no": "平成29年度（行情）答申第407号",
      "case_name": "過労自殺の労災認定が過失相殺なしで1億円以上の損害賠償責任が発生することと直結しつつあることに関する厚生労働省の問題意識が書いてある文書の不開示決定(不存在)に関する件",
      "result": "妥当（諮問庁の判断を維持）",
      "url": "https://jp.tailexi.org/hanrei/jyouhoutoushin-H29-gj-407",
      "source": "情報公開・個人情報保護審査会 答申（総務省）",
      "doc_kind": "答申"
    }
  ]
}

TOOL 06`get_law_article`Fetch articlesRead-only

Fetches articles of current statutes (e-Gov) — up to 20 articles of one statute per call, each with the number of decisions that refer to or cite it (cited_by_judgments). Besides the official title, abbreviations such as 民訴法, 労基法, 独禁法 and 個人情報保護法, or Traditional Chinese spellings, are accepted.

Parameters

Parameter	Type	Default	Description
`law`required	string	—	Statute name or abbreviation.
`articles`required	string[]	—	List of article numbers (up to 20), e.g. `["709", "710"]` or `["3の2"]`. Supplementary provisions: `附則52` (original) or `附則52(平成28年法律第15号)` (those of an amending act, as excerpted by e-Gov into the amended statute). Appended tables: `別表第一` (or `別表1`, `別表`).
`with_cases`	boolean	false	Also return the leading decisions citing each article (up to 5).
`as_of`	string	—	`YYYY-MM-DD`. Also returns the text in force on that date (`as_of_version`) and the amendments since (effective date and amending act). Pass a decision’s date to get the article as it stood then.

as_of_version.in_force_from is when that wording took effect. If it equals coverage_from (the start of the amendment data), it is not the effective date — the wording was already in force before then (see in_force_from_meaning).

text is the current text. Use as_of for the text at the time of a decision (amendment history built from e-Gov’s point-in-time texts; most statutes are covered from 2016–2017 onward, and earlier dates return before_coverage). Because of transitional provisions, it may still differ from the text the court actually applied.

Example

Call (arguments)

{
  "law": "民法",
  "articles": [
    "709",
    "710"
  ],
  "with_cases": true
}

Response (example, abridged)

{
  "law": "民法",
  "law_num": "明治二十九年法律第八十九号",
  "category": "法律",
  "last_amended": "令和8年6月24日",
  "egov_url": "https://laws.e-gov.go.jp/law/129AC0000000089/20260624_508AC0000000045",
  "articles": [
    {
      "article": "709条",
      "label": "第七百九条",
      "caption": "（不法行為による損害賠償）",
      "chapter": "第三編 債権 ／ 第五章 不法行為",
      "text": "故意又は過失によって他人の権利又は法律上保護される利益を侵害した者は、これによって生じた損害を賠償する責任を負う。",
      "cited_by_judgments": 2483,
      "url": "https://jp.tailexi.org/law/%E6%B0%91%E6%B3%95/709",
      "leading_cases": [
        {
          "id": "57514",
          "citation": "最二小判昭和31年7月20日民集10巻8号1059頁",
          "court": "最高裁判所第二小法廷",
          "date": "1956-07-20",
          "date_wareki": "昭和31年7月20日",
          "type": "判決",
          "case_no": "昭和29年(オ)第634号",
          "case_name": "慰籍料並に名誉回復請求",
          "result": "棄却",
          "reporter": "民集10巻8号1059頁",
          "cited_by": 86,
          "url": "https://jp.tailexi.org/hanrei/57514"
        }
      ]
    },
    {
      "article": "710条",
      "label": "第七百十条",
      "caption": "（財産以外の損害の賠償）",
      "chapter": "第三編 債権 ／ 第五章 不法行為",
      "text": "他人の身体、自由若しくは名誉を侵害した場合又は他人の財産権を侵害した場合のいずれであるかを問わず、前条の規定により損害賠償の責任を負う者は、財産以外の損害に対しても、その賠償をしなければならない。",
      "cited_by_judgments": 191,
      "url": "https://jp.tailexi.org/law/%E6%B0%91%E6%B3%95/710",
      "leading_cases": [
        {
          "id": "57744",
          "citation": "最一小判昭和41年6月23日民集20巻5号1118頁",
          "court": "最高裁判所第一小法廷",
          "date": "1966-06-23",
          "date_wareki": "昭和41年6月23日",
          "type": "判決",
          "case_no": "昭和37年(オ)第815号",
          "case_name": "名誉および信用毀損による損害賠償および慰藉料請求",
          "result": "棄却",
          "reporter": "民集20巻5号1118頁",
          "cited_by": 78,
          "url": "https://jp.tailexi.org/hanrei/57744"
        }
      ]
    }
  ],
  "note": "現行条文。判決当時の条文と異なる場合があります。"
}

TOOL 07`search_laws`Search statutesRead-only

Finds statutes by name or abbreviation and, at the same time, articles by their wording (the Constitution and Acts first). Use it when you don’t know where a provision lives.

Parameters

Parameter	Type	Default	Description
`query`required	string	—	Statute name or abbreviation, or words from the text (space = AND).
`category`	string	—	`憲法`Constitution `法律`Acts `政令`Cabinet Orders `勅令`Imperial Ordinances `府省令`Ministerial Ordinances `規則`Rules
`limit`	integer	10	Number of articles (up to 20).
`page`	integer	1	Page of articles (the statute list is on page 1 only). `total`, `page`, `pages` and `has_more` have the same shape as other lists. Doctrinal terms (e.g. 善管注意義務) return the statutory wording and source articles in `doctrine`; a former statute title returns the current statute in `old_name_of`.

Doctrinal terms can differ from the statutory wording: 善管注意義務, for instance, appears in the statutes as 善良な管理者の注意. If nothing comes back, search again using the statute’s own phrasing.

laws_total is the number of statutes whose names match (the full size of laws). total is the number of matching articles; articles_total carries the same value and is kept for compatibility with earlier versions.

Example

Call (arguments)

{
  "query": "善良な管理者の注意",
  "limit": 3
}

Response (example, abridged)

{
  "laws_total": 0,
  "articles": [
    {
      "law": "船舶の所有者等の責任の制限に関する法律",
      "article": "42条",
      "caption": "（注意義務）",
      "excerpt": "【管理】人は、【善良な管理者の注意】をもつてその職務を行わなければならない。",
      "url": "https://jp.tailexi.org/law/%E8%88%B9%E8%88%B6%E3%81%AE%E6%89%80%E6%9C%89%E8%80%85%E7%AD%8…"
    },
    {
      "law": "民法",
      "article": "644条",
      "caption": "（受任者の注意義務）",
      "excerpt": "受任者は、委任の本旨に従い、【善良な管理者の注意】をもって、委任事務を処理する義務を負う。",
      "url": "https://jp.tailexi.org/law/%E6%B0%91%E6%B3%95/644"
    },
    "…"
  ],
  "articles_total": 137
}

TOOL 08`search_guidance`Search guidanceRead-only

Searches the standards agencies use to interpret and apply the law: National Tax Agency interpretive circulars (所得税基本通達, 法人税基本通達, 措置法通達 and others), Personal Information Protection Commission guidelines and Q&A, Japan Fair Trade Commission guidelines, FSA supervisory guidelines, and MHLW notices on labour standards. Enter an article (所得税法36条) and the circulars interpreting it come first.

Parameters

Parameter	Type	Default	Description
`query`required	string	—	Terms (space = AND), an article (`所得税法36条`) or a circular number (`所基通36-1`).
`issuer`	string[]	—	`nta_tsutatsu`NTA circulars `ppc`Personal Information Protection Commission `jftc_guidelines`Japan Fair Trade Commission `fsa_guidelines`FSA supervisory guidelines, disclosure guidelines, insider trading and large shareholding Q&A `mhlw_tsuchi`MHLW notices `nta_qa`NTA Q&A rulings `nta_bunsho`NTA written rulings `moj_touki`MOJ registration circulars `mlit_guidelines`MLIT real estate & construction `caa_chikujo`CAA commentaries & guidelines `grayzone`Gray Zone answers `nta_jimu`NTA administrative guidelines `nta_kokuji`NTA public notices `nta_taxanswer`NTA Tax Answer `fsa_noact`FSA no-action letters `fsa_jirei`FSA enforcement casebooks `customs_kyoji`Customs advance rulings
`sort`	string	"relevance"	`relevance` (for an article-only query: documents interpreting the article first, then interpretive circulars and basic circulars, then Q&As …), `newest`, `oldest` (by issue, amendment or reference date; undated items last)
`year_from / year_to`	integer	—	Year range (Gregorian) of the issue, amendment or reference date. Undated items (current Q&As without per-item dates, etc.) are kept by default and counted in `undated_kept` / `notes`.
`include_undated`	boolean	true	Set `false` to drop undated items when filtering by year.
`page / limit`	integer	1 / 10	Page (up to 50) and results per page (up to 20).

For an article query, each result has relation_to_article: interprets = interprets the article; mentions = only mentions it in the text or notes (the subject may differ; hint says so when nothing interprets it). A circular number (法人税基本通達9-2-32, full-width digits too) returns that circular plus documents citing it. Amounts match regardless of style (1万円 ⇔ 10,000円). With zero hits, hint lists the counts with one term dropped.

Guidance is the administration’s interpretation. It does not directly bind the public or the courts. Content is as of collection; check the source (source_url) for the latest version.

Example

Call (arguments)

{
  "query": "所得税法36条",
  "limit": 3
}

Response (example, abridged)

{
  "total": 115,
  "page": 1,
  "pages": 39,
  "notes": ["所得税法36条を解釈・言及する通達として検索。"],
  "results": [
    {
      "id": "nta-tsutatsu:shotoku-kihon:36-1",
      "cite": "所基通36-1",
      "caption": "（収入金額）",
      "collection": "所得税基本通達",
      "issuer": "国税庁",
      "type": "通達",
      "chapter": "第2編 居住者の納税義務 ／ 第1章 課税標準及びその計算並びに所得控除 ／ 第1節 各種所得の金額の計算 ／ 第2款 所得金額の計算の通則 ／ 法第36条《収入金額》関係 ／ 〔収入金額〕",
      "excerpt": "法第36条第1項に規定する「収入金額とすべき金額」又は「総収入金額に算入すべき金額」は、その収入の基因となった行為が適法であるかどうかを問わない。",
      "url": "https://jp.tailexi.org/tsutatsu/nta-tsutatsu%3Ashotoku-kihon%3A36-1"
    },
    {
      "id": "nta-tsutatsu:shotoku-kihon:36-2",
      "cite": "所基通36-2",
      "caption": "（利子所得の収入金額の収入すべき時期）",
      "collection": "所得税基本通達",
      "issuer": "国税庁",
      "type": "通達",
      "chapter": "第2編 居住者の納税義務 ／ 第1章 課税標準及びその計算並びに所得控除 ／ 第1節 各種所得の金額の計算 ／ 第2款 所得金額の計算の通則 ／ 法第36条《収入金額》関係 ／ 〔収入金額の収入すべき時期〕",
      "excerpt": "利子所得の収入金額の収入すべき時期は、法第36条第3項に規定するものを除き、それぞれ次に掲げる日によるものとする。 (1) 定期預金（貯金及び令第2条第1号《預貯金の範囲》に掲げる貯蓄金でこれに類するものを含む。）の利子については、次に掲げる日 イ その契約により定められた預入期…",
      "url": "https://jp.tailexi.org/tsutatsu/nta-tsutatsu%3Ashotoku-kihon%3A36-2"
    },
    {
      "id": "nta-tsutatsu:shotoku-kihon:36-3",
      "cite": "所基通36-3",
      "caption": "（振替記載等を受けた公社債）",
      "collection": "所得税基本通達",
      "issuer": "国税庁",
      "type": "通達",
      "chapter": "第2編 居住者の納税義務 ／ 第1章 課税標準及びその計算並びに所得控除 ／ 第1節 各種所得の金額の計算 ／ 第2款 所得金額の計算の通則 ／ 法第36条《収入金額》関係 ／ 〔収入金額の収入すべき時期〕",
      "excerpt": "社債、株式等の振替に関する法律の規定により振替記載等を受けた公社債及び国債に関する法律又は廃止前の社債等登録法の規定により登録した公社債は、法第36条第3項に規定する無記名の公社債には該当しない。",
      "url": "https://jp.tailexi.org/tsutatsu/nta-tsutatsu%3Ashotoku-kihon%3A36-3"
    }
  ],
  "note": "通達・ガイドライン等は、行政機関が法令の解釈や運用の考え方を示したもので、国民や裁判所を直接拘束するものではありません。掲載時点の内容です。最新の内容は出典元でご確認ください。"
}

TOOL 09`get_guidance`Read a guidance documentRead-only

Returns one guidance document: the text (question and answer, for Q&A), notes, issuance and amendments, the articles it interprets (interprets), the articles it mentions, related NTA circulars (related_tsutatsu), and the attribution. Inquiries in written rulings, Gray Zone answers and similar (written by the inquirer) are returned in full in question; the original is at question_source_url.

Parameters

Parameter	Type	Default	Description
`id`required	string	—	The `id` from `search_guidance`, e.g. `nta-tsutatsu:shotoku-kihon:36-1`

Example

Call (arguments)

{
  "id": "nta-tsutatsu:shotoku-kihon:36-1"
}

Response (example, abridged)

{
  "id": "nta-tsutatsu:shotoku-kihon:36-1",
  "cite": "所基通36-1",
  "caption": "（収入金額）",
  "collection": "所得税基本通達",
  "issuer": "国税庁",
  "type": "通達",
  "category": "基本通達",
  "chapter_path": [
    "第2編 居住者の納税義務",
    "第1章 課税標準及びその計算並びに所得控除",
    "第1節 各種所得の金額の計算",
    "第2款 所得金額の計算の通則",
    "法第36条《収入金額》関係",
    "〔収入金額〕"
  ],
  "issued": "昭和45年7月1日 直審（所）30（例規）（審）",
  "collection_updated": "令和8年6月30日付通達まで掲載",
  "text": "法第36条第1項に規定する「収入金額とすべき金額」又は「総収入金額に算入すべき金額」は、その収入の基因となった行為が適法であるかどうかを問わない。",
  "interprets": ["所得税法36条"],
  "url": "https://jp.tailexi.org/tsutatsu/nta-tsutatsu%3Ashotoku-kihon%3A36-1",
  "source_url": "https://www.nta.go.jp/law/tsutatsu/kihon/shotoku/05/01.htm#a-01",
  "attribution": "出典：国税庁ホームページ「所得税基本通達」（https://www.nta.go.jp/law/tsutatsu/kihon/shotoku/05/01.htm#a-01）を加工して作成（加工：TaiLexi AI）",
  "note": "通達・ガイドライン等は、行政機関が法令の解釈や運用の考え方を示したもので、国民や裁判所を直接拘束するものではありません。掲載時点の内容です。最新の内容は出典元でご確認ください。"
}

TOOL 10`get_legislative_history`Get legislative historyRead-only

With article, returns the government's answers in the Diet about that article (ministers, government witnesses and delegates, and sponsors of member bills), each with the preceding question and any minister's confirmation. Every answer carries why it was matched (basis: “mentions 第548条の2”, “contains 「定型約款」”), an excerpt of the original minutes, speaker, house, committee, issue, page and remark number, a court-style citation and the NDL Diet Record URL; plus the relevant paragraph of the reasons for the bill, matching supplementary-resolution items and the bill. Without article, returns the statute's enactment and amendment history (Japanese Law Index). Article matching is rule-based (article numbers, headings and defined terms; no AI) and can be wrong; answers matched on wording alone have confidence low.

Parameters

Parameter	Type	Default	Description
`law`required	string	—	Statute name or abbreviation, e.g. `民法`, `会社法`, `個人情報保護法`.
`article`	string	—	Article number, e.g. `548の2`, `709`. Omit for the statute's history.
`limit`	integer	5 / 60	Count. Answers for an article: default 5, up to 20. A statute's history (no `article`): default 60, up to 100.
`offset`	integer	0	Where to start. When `has_more` is true, pass `next_offset` (both answers and history return `total`, `offset`, `limit`, `page`, `pages`, `has_more`, `next_offset`).

Answers are interpretive material. Diet answers and supplementary resolutions are not legally binding. Article-level answers cover the statutes most cited by courts (Civil Code, Penal Code, Companies Act, Code of Civil Procedure, Patent Act, Personal Information Protection Act and others) and exclude the Imperial Diet (before 1947). There is no search by individual speaker (Copyright Act art. 40(1) proviso).

answers_total (article answers) and amendments_total (statute history) carry the same value as total and are kept for compatibility with earlier versions. counts is the number of Diet remarks containing the article number or caption terms — not the number of answers in answers.

Example

Call (arguments)

{
  "law": "民法",
  "article": "548の2",
  "limit": 3
}

TOOL 11`search_diet_records`Search Diet deliberationsRead-only

Searches Diet remarks made while deliberating bills (explanations, questions, debate, supplementary resolutions; about 4 million remarks since the 1st Diet). Narrow by law (deliberations on bills about that statute), role (government, members, witnesses), house and dates. Each result has the speaker, role, sitting, issue, date, page, remark number, the matched text (in 【】), a court-style citation, and links to the NDL Diet Record and our reader.

Parameters

Parameter	Type	Default	Description
`query`required	string	—	Terms (space = AND; each term matched as a phrase).
`law`	string	—	Only deliberations on bills about this statute.
`role`	string	—	`gov` (government side), `member` (members), `ref` (witnesses)
`house`	string	—	`衆議院` `参議院`
`date_from / date_to`	string	—	YYYY-MM-DD
`limit`	integer	10	Results (up to 20).

Example

Call (arguments)

{
  "query": "定型約款 事業者間",
  "law": "民法",
  "role": "gov",
  "limit": 3
}

06Query syntax

Syntax	Meaning	Example
`A B`	All terms (AND)	`安全配慮義務過労`
`A OR B`	Either term	`解雇 OR 雇止め`
`-A`	Exclude A	`名誉毀損 -刑事`
`"A B"`	Exact phrase	`"公共の利害に関する事実"`
Case number	Decisions in that case	`平成24年(ク)第984号`、`令和5(受)1234`
Citation	Identified by court, date and law report	`最大判昭和48年4月4日`、`最二小判平26・9・5`、`民集67巻6号1320頁`
Article	Decisions referring to or citing it	`民法709条`、`会社法423条1項`

Spelling variants — old and Traditional Chinese character forms, okurigana, か月／ヶ月 and the like — are normalized automatically. Searching with the legal terms that judgments actually use gives better results.

07Citation formats

Every decision carries three citation styles. The examples below are the 1973 Grand Bench judgment striking down the aggravated penalty for parricide.

Style	Example
Standard (`citation`)	`最大判昭和48年4月4日刑集27巻3号265頁`
Short (`citation_short`)	`最大判昭48・4・4刑集27巻3号265頁`
Judgment style (`citation_judgment_style`)	`最高裁昭和45年(あ)第1310号同48年4月4日大法廷判決・刑集27巻3号265頁`

Decisions not published in a law report are cited as “(case number) 裁判所ウェブサイト” — that is, the Courts in Japan website.

08Coverage and updates

Source	Count	Contents
Supreme Court	29,468	Grand and Petty Bench judgments and decisions (with Minshū, Keishū, Shūmin and Shūkei references)
High Courts	13,760	High Court cases, including administrative and labour cases
IP High Court	6,438	Suits against JPO decisions, infringement suits, etc.
District Courts and others	17,798	Lower-court decisions (including Family and Summary Courts)
Courts in Japan website, subtotal	67,464	1947 onward (as published in the website’s 裁判例検索)
Labour Commission orders and cases	8,039	Central Labour Relations Commission database (unfair labour practice orders, etc.)
Tax litigation reports	3,309	National Tax Agency, 税務訴訟資料 (tax judgments; the 432 also on the Courts website are listed as an additional reporter)
National Tax Tribunal rulings	2,695	Published rulings and summaries
JFTC decisions	2,421	JFTC decisions database (judgments, decisions and hearing decisions), plus cease-and-desist and surcharge orders
Review Board reports	9,997	Information Disclosure and Personal Information Protection Review Board, MIC (FY2016 onward)
Shōmu Geppō	1,258	Ministry of Justice litigation case database (the 957 duplicates are listed as an additional reporter)
Administrative appeal rulings	10,029	MIC administrative appeal rulings and reports database (2016 onward)
FSA surcharge hearings	703	Summaries of decisions
Labour Insurance Appeal Committee	3,398	MHLW list of rulings (workers' compensation and employment insurance)
Social Insurance Appeal Committee	290	MHLW selected rulings (pensions and health insurance)
JPO trial and appeal decisions	51,585	JPO trial decision gazette (October 2022 onward, as published)
Japan Marine Accident Tribunal rulings	390	Tribunal and regional offices (currently published)
Premiums and Representations Act orders	237	Consumer Affairs Agency press releases (FY2021 onward)
Environmental Dispute Coordination Commission rulings	358	Liability and causation rulings
Nuclear Damage Compensation ADR settlements	2,285	Published settlement cases
SESC recommendations	698	FY2009 onward
Pre-war and early post-war law reports (OCR)	27,380	OCR of the National Diet Library Digital Collections (Great Court of Cassation and others; decisions from 1940 onward have bibliographic data and a link only)
Case law, total	192,536	Filter by source with the `source` parameter of `search_judgments`
Statutes	8,984	Current Constitution, Acts, Cabinet Orders, Ministerial Ordinances and Rules (243,568 articles); amendment history is being extended outward from the major statutes
Guidance	71,119	Customs advance rulings 13,422 · NTA (circulars 12,721, Q&A 1,934, administrative guidelines 1,222, Tax Answer 761, written rulings 731, public notices 420, invoice-system Q&A 171) · MHLW notices 28,647 (in progress) · FSA (guidelines incl. disclosure guidelines 3,443, casebooks 2,368, no-action letters 98) · JFTC 1,283 · MOJ registration circulars 983 · PPC 885 · CAA 929 · MLIT 501 · Gray Zone answers 198

New decisions on the Courts in Japan website are imported daily (late night, Japan time). Other official records and amendment history update in the same window.
Amendment history (as_of) covers what e-Gov’s history data holds, and the start differs by statute (mostly 2016–2017; the Civil Code from the amendment in force on 13 October 2016). Earlier dates return before_coverage.
Known gaps: Premiums and Representations Act orders only from April 2021 (what the Consumer Affairs Agency site still publishes); tax litigation reports from 2007 (assessment) and 2009 (collection); NDL law reports have bibliographic data and a link only for decisions from 1940 onward. The Labour and Social Insurance Appeal boards, customs advance rulings and Gray Zone answers update weekly. Live counts, periods and last-update dates per source are on the Sources page.
Citation counts identify the cited decision from Supreme Court case numbers, or from date, bench and volume/page references, in the texts we hold. Citations in sources outside the collection (law journals and the like) are not counted.
Decision texts are machine-extracted from PDFs; for formal citation, check the original at pdf_url.

09Rate limits

Scope	Limit
Per client IP, per minute	120 requests
Per client IP, per day	10,000 requests
Whole service, per minute	1,200 requests

Over the limit, the server returns HTTP 429 with Retry-After (in seconds). Search results are cached briefly, so repeating a call is fast.

10Errors

Type	Meaning	What to do
Tool error	`isError: true` with an explanation in Japanese (e.g. statute not found, article number unreadable)	Fix the arguments as described
Invalid arguments	`isError: true` with a short message in Japanese (e.g. `引数エラー（search_judgments）：page は 1 以上で指定してください。`)	Check the types and ranges in the tool schema. `court_level` also accepts full names such as 最高裁判所
Malformed JSON	JSON-RPC `-32700` (`id` is `null`)	Check the request body
Request with `"id": null`	JSON-RPC `-32600` (Invalid Request, HTTP 400). A notification (no `id` at all) gets HTTP 202	Use a string or number for `id`
HTTP 429	Rate limit exceeded	Retry after `Retry-After` seconds
HTTP 502 / 503	Temporary overload or connection problem	Wait a moment and retry

11Protocol

The server is stateless; every request stands on its own. You can also send JSON-RPC directly, without an SDK.

Terminal

curl -s https://jp.tailexi.org/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Terminal

curl -s https://jp.tailexi.org/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"search_judgments","arguments":{"query":"民法709条 因果関係","limit":3}}}'

12Sources and license

Case law: Courts in Japan, 裁判例検索 (https://www.courts.go.jp/hanrei/). Under Article 13 of Japan’s Copyright Act, judgments are not subject to copyright. Points decided, summaries and statutes referred to are as published by the courts. Some data comes from japanese-law-analysis/data_set (CC0 1.0).
Statutes: created by TaiLexi AI from data provided by e-Gov 法令検索（デジタル庁） (https://laws.e-gov.go.jp/), under the Public Data License (公共データ利用規約第 1.0 版). The Official Gazette (Kanpō) is authoritative; where the two differ, the Gazette prevails.
Other official records: processed by TaiLexi AI from the following sources (named as published): 税務訴訟資料（国税庁）、公表裁決事例（国税不服審判所）、労働委員会関係命令・裁判例データベース（中央労働委員会）、訟務重要判例集データベース（法務省）、審決等データベース及びホームページ（公正取引委員会）、課徴金審判の決定（金融庁）、情報公開・個人情報保護審査会の答申（総務省）、行政不服審査裁決・答申検索データベース（総務省）.
Case notes and literature: bibliographic data from the National Diet Library’s 雑誌記事索引 (Japanese Periodicals Index; CC BY 4.0, https://ndlsearch.ndl.go.jp/). Matching to decisions and the citation format are added by TaiLexi AI. Attribution: 出典：国立国会図書館雑誌記事索引（CC BY 4.0）.
get_judgment returns a per-document attribution in attribution; include it whenever you quote the document in an answer or elsewhere.
Some records that may contain personal names (JFTC criminal judgments with no anonymized version on the Courts website) are returned without their text (full_text_withheld) — only bibliographic data, search excerpts and the source URL.
Citation formats, subject areas and citation counts are added by TaiLexi AI. This service is not affiliated with, produced by or endorsed by any of these bodies, and nothing here is legal advice.

13Changelog

Date	Version	Changes
2026-10-11	`1.7.0`	`search_judgments` gains `detail` (default `auto`: six or more results come back `compact`, with only the opening of the points decided; the previous shape is `full`) and reports the `detail` it used. `analyze_issue` ranks leading precedents by citations near the issue’s terms (`cited_near_terms`) and lists precedents cited by Labour Relations Commission court cases separately in `leading_precedents_labor_commission`. `get_commentary` citations use the abbreviated title and serial number for serially numbered journals (`判タ1181号116頁`) and mark unsigned research-judge commentaries as “（調査官解説）”. `get_legislative_history` adds `predecessor` for articles moved from another statute (the predecessor article and the bill that created it, e.g. 労働契約法16条 ← 労働基準法18条の2). The `notes` in this page’s examples now show the real shape (an array of strings).
2026-10-11	`1.6.2`	Tool definitions (`tools/list`) slimmed from about 28.6 KB to about 17.7 KB (shorter descriptions; full details on this page). Requests with `"id": null` now get `-32600`. `analyze_issue` notes when, with fewer than five matches, `most_cited_articles` includes articles cited only once. Counts on this page are now read from the index.
2026-10-10	`1.6.1`	Unified paging: `get_legislative_history` (statute history now pages with `offset`) and `get_commentary` return `total`, `offset`, `limit`, `page`, `pages`, `has_more`, `next_offset`; `search_laws` gains `page`. `search_laws` adds `doctrine` (doctrinal term → statutory wording and source articles), `old_name_of` (former titles) and a zero-hit `hint`. `search_guidance` adds `relation_to_article`, `include_undated`, and understands circular numbers and amount formats. Documented `doc_type`, `exact_terms` and the syntax for supplementary provisions and appended tables.
2026-10-10	`1.6.0`	Added `get_commentary` (case notes and literature: NDL Japanese Periodicals Index records with Japanese legal citations). `get_judgment` now returns `commentary` (first five) and `commentary_total`; `search_judgments` results carry `commentary_count`.
2026-10-10	`1.5.1`	List tools now share `total`, `page`, `pages` and `has_more`, and an out-of-range page returns `results: []`; `search_judgments` pages correctly when `limit` is under 20. `get_judgment` returns `text_status` and `alt_id_with_text` when there is no text. `get_law_article` echoes `requested` for each article, and `as_of_version` adds `in_force_from_meaning` and `coverage_from`. `court_level` accepts full names (最高裁判所, etc.). `search_diet_records` gains `page`. Argument errors are short Japanese messages; malformed JSON gets `id: null`. `find_similar_judgments` is withheld until its accuracy is confirmed.
2026-10-09	`1.5.0`	Added `find_similar_judgments` (similar cases from text embeddings, with shared provisions and terms as the reason). `get_judgment` now returns `similar` (top five).
2026-10-09	`1.4.1`	New content (`source` in `search_judgments`): Environmental Dispute Coordination Commission liability and causation rulings (`kouchoi`), Nuclear Damage Compensation ADR Center settlements and reasons for settlement proposals (`genbai`), and SESC recommendations (`sesc`). Added the field `kind` value 環境 (environment).
2026-10-09	`1.4.0`	Added `get_legislative_history` (Diet answers, reasons and supplementary resolutions for an article; a statute's enactment and amendment history) and `search_diet_records` (search Diet remarks in bill deliberations).
2026-10-08	`1.3.0`	New content: JPO trial and opposition decisions and Marine Accident Tribunal rulings (`source`); NTA administrative guidelines, public notices and Tax Answer, all FSA supervisory guidelines, no-action letters and casebooks, customs advance rulings, the Specified Commercial Transactions Act commentary and all MHLW notices (`issuer`). Inquiries in written rulings and Gray Zone answers are now full text. Added the `海事` subject area.
2026-10-08	`1.2.0`	New content: Labour and Social Insurance Appeal Committee rulings and Premiums and Representations Act orders (`source` in `search_judgments`); NTA Q&A and written rulings, MOJ registration circulars, MLIT and CAA guidelines, and Gray Zone answers (`issuer` in `search_guidance`). Added the `社会保障` and `消費者` subject areas.
2026-10-08	`1.1.0`	Added `search_guidance` and `get_guidance` (NTA interpretive circulars, PPC and JFTC guidelines, FSA supervisory guidelines, MHLW notices). Added `as_of` to `get_law_article` (the text in force on a given date, with amendment history) and `source` to `search_judgments` (tax litigation reports, Shōmu Geppō, National Tax Tribunal rulings, Labour Commission orders, JFTC decisions, FSA surcharge hearings, review board reports, administrative appeal rulings). `get_judgment` now returns an `attribution`.
2026-10-08	`1.0.0`	Initial release with six tools (search_judgments, get_judgment, get_cited_by, analyze_issue, get_law_article, search_laws).

Contact: [email protected]　Privacy policy

Japanese Law MCP

01Overview

02Quickstart

Example prompts

A typical sequence

03Client setup

04Use from an API or SDK

05Tools

TOOL 01search_judgmentsSearch case lawRead-only

Parameters

Returns

Example

TOOL 02get_judgmentRead a decisionRead-only

Parameters

Returns

Example

TOOL 03get_cited_byCiting decisionsRead-only

Parameters

Example

TOOL 04get_commentaryCase notes and literatureRead-only

Parameters

Returns

Example

TOOL 05analyze_issueSurvey an issueRead-only

Parameters

Example

TOOL 06get_law_articleFetch articlesRead-only

Parameters

Example

TOOL 07search_lawsSearch statutesRead-only

Parameters

Example

TOOL 08search_guidanceSearch guidanceRead-only

Parameters

Example

TOOL 09get_guidanceRead a guidance documentRead-only

Parameters

Example

TOOL 10get_legislative_historyGet legislative historyRead-only

Parameters

Example

TOOL 11search_diet_recordsSearch Diet deliberationsRead-only

Parameters

Example

06Query syntax

07Citation formats

08Coverage and updates

09Rate limits

10Errors

11Protocol

12Sources and license

13Changelog

TOOL 01`search_judgments`Search case lawRead-only

TOOL 02`get_judgment`Read a decisionRead-only

TOOL 03`get_cited_by`Citing decisionsRead-only

TOOL 04`get_commentary`Case notes and literatureRead-only

TOOL 05`analyze_issue`Survey an issueRead-only

TOOL 06`get_law_article`Fetch articlesRead-only

TOOL 07`search_laws`Search statutesRead-only

TOOL 08`search_guidance`Search guidanceRead-only

TOOL 09`get_guidance`Read a guidance documentRead-only

TOOL 10`get_legislative_history`Get legislative historyRead-only

TOOL 11`search_diet_records`Search Diet deliberationsRead-only