Legal Docs Client

A TypeScript client library for accessing legal documents from the Case Law Explorer API.

Each data source is exposed through its own typed endpoint: Rechtspraak (Dutch case law) and ECHR (European Court of Human Rights).

Installation

npm install legal-docs-client

Usage

Basic Setup

import { createLegalDocsClient } from 'legal-docs-client';

const client = createLegalDocsClient({
  apiKey: process.env.CITATIONS_API_KEY
});

Fetching Rechtspraak Documents

fetchRechtspraak queries Dutch case law (Rechtspraak) citation networks:

const documents = await client.fetchRechtspraak({
  degreesSource: 0,
  degreesTarget: 0,
  dateStart: "1900-01-01",
  dateEnd: "2026-03-10",
  docTypes: ["DEC"],
  attributesToFetch: "ALL",
  keywords: ["armenia"],
  selectedLawsIntersect: true,
});

console.log(documents);

Fetching Documents with Statistics

You can automatically compute statistics for the fetched documents by passing true as the second parameter:

const documents = await client.fetchRechtspraak({
  degreesSource: 1,
  degreesTarget: 1,
  dateStart: "2020-01-01",
  dateEnd: "2024-12-31",
  docTypes: ["DEC"],
  eclis: ["ECLI:NL:HR:2021:1234"],
}, true); // computeStatistics = true

// Each document will have a statistics property with centrality metrics
console.log(documents[0].data.statistics);
/*
{
  parent: "ECLI:NL:HR:2021:1234",
  degree: 5,
  inDegree: 2,
  outDegree: 3,
  degreeCentrality: 0.8,
  inDegreeCentrality: 0.4,
  outDegreeCentrality: 0.6,
  betweennessCentrality: 0.5,
  closenessCentrality: 0.7,
  relativeInDegree: 0.4,
  community: 0,
  year: 2021,
  pageRank: 0.25
}
*/

Computing Statistics

You can compute network statistics (centrality metrics) for a set of documents:

// First, fetch some documents
const documents = await client.fetchRechtspraak({
  degreesSource: 1,
  degreesTarget: 1,
  eclis: ["ECLI:NL:HR:2021:1234"],
});

// Then compute statistics
const statistics = await client.computeStatistics(documents);

console.log(statistics);
/*
[
  {
    id: "ECLI:NL:HR:2021:1234",
    parent: "ECLI:NL:HR:2020:5678",
    degree: 5,
    inDegree: 2,
    outDegree: 3,
    degreeCentrality: 0.8,
    inDegreeCentrality: 0.4,
    outDegreeCentrality: 0.6,
    betweennessCentrality: 0.5,
    closenessCentrality: 0.7,
    relativeInDegree: 0.4,
    community: 0,
    year: 2021,
    pageRank: 0.25
  },
  // ... more statistics for other documents
]
*/

The statistics include various centrality measures:

• degree: Total number of connections (citations + cited by)
• inDegree: Number of documents citing this one
• outDegree: Number of documents this one cites
• degreeCentrality: Normalized degree centrality
• inDegreeCentrality: Normalized in-degree centrality
• outDegreeCentrality: Normalized out-degree centrality
• betweennessCentrality: Measure of how often a document lies on the shortest path between other documents
• closenessCentrality: Measure of how close a document is to all other documents
• relativeInDegree: Ratio of in-degree to total degree
• pageRank: PageRank score indicating importance in the citation network
• community: Community/cluster identifier
• year: Year from the document's decision date

Getting Full Text

const fullTextDocs = await client.getRechtspraakFullText(['ECLI:NL:HR:2005:AO9006', 'ECLI:NL:RBSGR:2012:BY5532']);

console.log(fullTextDocs);
// [{ ecli, fullText, fullTextAvailable, message? }, ...]

Fetching ECHR Documents

fetchEchr queries HUDOC (European Court of Human Rights) citation networks. At least one search criterion (keyword, ECLI, application number, or article) is required:

const documents = await client.fetchEchr({
  degreesSource: 1,
  degreesTarget: 1,
  keywords: ["Armenia"],
  attributesToFetch: "MINIMAL",
});

console.log(documents);

Filter by violated/applied articles and respondent state:

const documents = await client.fetchEchr({
  degreesSource: 1,
  degreesTarget: 1,
  article_violated: ["6", "8"],
  article_violated_mode: "OR",
  respondent_state: ["GRC"],
  pageSize: 100,
});

Statistics can be computed the same way as for Rechtspraak, by passing true as the second parameter, or afterwards via client.computeStatistics(documents).

Getting ECHR Full Text

const fullTextDocs = await client.getEchrFullText(['ECLI:CE:ECHR:2000:1026JUD003098596']);

console.log(fullTextDocs);
// [{ ecli, language, itemid, fullText, fullTextAvailable, message?, languages? }, ...]

By default the API picks a language (English preferred, then French) and returns every available language version in languages. Request a specific language instead:

const fullTextDocs = await client.getEchrFullText(
  ['ECLI:CE:ECHR:2000:1026JUD003098596'],
  'FRE',
);

Fetching Laws

const laws = await client.fetchLaws('Art. 7:669 BW');

console.log(laws);

Environment Configuration

This package requires an API token from the Case Law Explorer API for document requests.

Setup Instructions

1. Install dotenv (if working in Node.js):

npm install dotenv

2. Create a .env file in your project root:

CITATIONS_API_KEY=your_api_token_here

3. Load environment variables in your application:

import 'dotenv/config';
import { createLegalDocsClient } from 'legal-docs-client';

const client = createLegalDocsClient({
  apiKey: process.env.CITATIONS_API_KEY
});

Note: For Vite projects, use import.meta.env.VITE_CITATIONS_API_KEY instead and prefix your .env variable with VITE_.

Getting an API Token

New API keys can be generated at: https://api.caselawexplorer.tech/login.html?next=/account.html

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.