Agent skill

Caselaw Access API

by wentorai in wentorai/research-plugins

Query 360+ years of US case law via the Harvard Caselaw Access Project

MITAuto-check passedLegal & Compliance

Install Caselaw Access API

skills CLI
$ npx skills add wentorai/research-plugins --skill caselaw-access-api -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install wentorai/research-plugins caselaw-access-api --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/domains/law/caselaw-access-api .claude/skills/caselaw-access-api && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
caselaw-access-api
GitHub stars
298
Used in
1 other repo
Token cost
~1.1k tokens
SKILL.md length
194 words
Files
1
Skills in repo
405
Repo updated
First seen
Licence
MIT

At a glance

Query 360+ years of US case law via the Harvard Caselaw Access Project

  • Tasks that involve Legal research
  • SKILL.md covers Overview, API Endpoints, Python Usage and Bulk Data Access, plus 3 more sections
  • Calls curl; reaches api.case.law and case.law

What it does

Caselaw Access API is an agent skill from wentorai/research-plugins. Query 360+ years of US case law via the Harvard Caselaw Access Project

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Legal & Compliance, covering Legal research. The repository describes itself as: 350+ academic research skills, MCP configs, and plugins for Research-Claw and AI agents. The licence is MIT.

When your agent uses it

  • Tasks that involve Legal research

Example prompts

  • “/caselaw-access-api”

Requirements

  • Python 3
  • A credential in YOUR_API_KEY
  • A credential in YOUR_TOKEN

What it can do on your machine

Read from SKILL.md and the folder at commit bf44b3c. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • curl

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • api.case.law
    • case.law

    Also links to:

    • lil.law.harvard.edu

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Caselaw Access API loads about 1.1k tokens when it runs. Until then it costs about 22 tokens; SKILL.md has 194 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~22
When it runs · the whole SKILL.md, loaded when a task matches
~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from wentorai/research-plugins at commit bf44b3c, republished under its MIT licence (© wentorai). 194 words, ~1,133 tokens.

Download SKILL.mdSave it as .claude/skills/caselaw-access-api/SKILL.md (or your agent's skills folder).
name
caselaw-access-api
description
Query 360+ years of US case law via the Harvard Caselaw Access Project

Caselaw Access Project API

Overview

The Caselaw Access Project (CAP) by Harvard Law School provides free access to 6.9 million US court opinions spanning 360+ years. The REST API enables searching, filtering, and downloading full-text case opinions from all federal and state courts. No authentication required for metadata; API key (free registration) required for full text of post-1923 cases.

API Endpoints

Base URL
https://api.case.law/v1/
Cases
bash
# Search cases by keyword
curl "https://api.case.law/v1/cases/?search=free+speech&decision_date_min=2020-01-01"

# Get a specific case by ID
curl "https://api.case.law/v1/cases/12345678/"

# Filter by jurisdiction and court
curl "https://api.case.law/v1/cases/?jurisdiction=us&court=us-sup-ct&search=miranda+rights"

# Filter by date range
curl "https://api.case.law/v1/cases/?decision_date_min=2015-01-01&decision_date_max=2025-12-31"

# Get full text (requires API key for post-1923)
curl -H "Authorization: Token YOUR_API_KEY" \
  "https://api.case.law/v1/cases/12345678/?full_case=true"
Query Parameters
ParameterDescriptionExample
searchFull-text searchsearch=due+process
jurisdictionFilter by jurisdiction slugjurisdiction=cal (California)
courtFilter by court slugcourt=us-sup-ct
decision_date_minEarliest datedecision_date_min=2020-01-01
decision_date_maxLatest datedecision_date_max=2025-12-31
citeSearch by citationcite=410+U.S.+113
name_abbreviationCase namename_abbreviation=Roe+v.+Wade
orderingSort resultsordering=-decision_date
page_sizeResults per page (max 100)page_size=50
full_caseInclude full textfull_case=true
Courts and Jurisdictions
bash
# List all courts
curl "https://api.case.law/v1/courts/"

# List all jurisdictions
curl "https://api.case.law/v1/jurisdictions/"

# List all reporters (case report series)
curl "https://api.case.law/v1/reporters/"

Python Usage

python
import requests

BASE_URL = "https://api.case.law/v1"

def search_cases(query: str, jurisdiction: str = None,
                 court: str = None, max_results: int = 20) -> list:
    """Search US case law."""
    params = {"search": query, "page_size": min(max_results, 100)}
    if jurisdiction:
        params["jurisdiction"] = jurisdiction
    if court:
        params["court"] = court

    resp = requests.get(f"{BASE_URL}/cases/", params=params)
    resp.raise_for_status()
    data = resp.json()

    cases = []
    for case in data.get("results", []):
        cases.append({
            "id": case["id"],
            "name": case["name_abbreviation"],
            "citation": case["citations"][0]["cite"] if case.get("citations") else None,
            "court": case["court"]["name"],
            "date": case["decision_date"],
            "url": case["frontend_url"]
        })
    return cases

# Search Supreme Court cases
results = search_cases("fourth amendment", court="us-sup-ct")
for case in results:
    print(f"{case['citation']}: {case['name']} ({case['date']})")

Bulk Data Access

For large-scale research, download bulk datasets instead of querying the API:

bash
# Bulk data available at:
# https://case.law/bulk/download/
# Formats: JSON (full case data) or text-only
# Organized by jurisdiction and reporter

Key Jurisdictions

SlugJurisdictionCases
usFederal (all)~1.5M
us-sup-ctUS Supreme Court~65K
calCalifornia~500K
nyNew York~600K
texTexas~300K
illIllinois~250K

Authentication

1. Register at https://case.law/user/register/
2. Get API token from your account page
3. Include in requests: Authorization: Token YOUR_TOKEN

Free accounts get full text for pre-1923 cases. Post-1923 full text requires an API token (still free).

References

© wentorai, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/domains/law/caselaw-access-api of wentorai/research-plugins.

Open the folder on GitHubat commit bf44b3c

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in wentorai/research-plugins, which our catalogue first saw on October 7, 2026.

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Tw Legal RAGaa0101181514/tw-legal-rag328—~580Automated safety check: PassCustom licence
Design Award SearchSeanJ1ang/design-judge-skills712—~3kAutomated safety check: PassApache-2.0
China Lawyer AnalystCSlawyer1985/china-lawyer-analyst196—~3.3kAutomated safety check: PassNone
Billing And Litigation BudgetTHUYRan/Legal-Skills-Chinese874—~5kAutomated safety check: PassNone
Legal Issue ResearchGolden2002/legal-research-skill156—~6.8kAutomated safety check: PassMIT

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Questions about Caselaw Access API

What does Caselaw Access API do?

Query 360+ years of US case law via the Harvard Caselaw Access Project. Caselaw Access API is an agent skill from wentorai/research-plugins.

When should I use Caselaw Access API?

Caselaw Access API fits situations like: tasks that involve Legal research.

How do I install Caselaw Access API in Claude Code?

Run `npx skills add wentorai/research-plugins --skill caselaw-access-api -a claude-code`. Or copy the skill folder (skills/domains/law/caselaw-access-api in wentorai/research-plugins) into .claude/skills/caselaw-access-api in your project. Claude Code loads it when a task matches its description.

How do I install Caselaw Access API in Codex?

Run `npx skills add wentorai/research-plugins --skill caselaw-access-api -a codex`. Or copy the skill folder (skills/domains/law/caselaw-access-api in wentorai/research-plugins) into .agents/skills/caselaw-access-api in your project. Codex loads it when a task matches its description.

Can I use Caselaw Access API in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add wentorai/research-plugins --skill caselaw-access-api -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/caselaw-access-api, .gemini/skills/caselaw-access-api, .github/skills/caselaw-access-api and .opencode/skills/caselaw-access-api in your project.

What does Caselaw Access API need to run?

Going by SKILL.md and its folder, Caselaw Access API needs the command-line tools its instructions call (curl). Our summary lists: Python 3; A credential in YOUR_API_KEY; A credential in YOUR_TOKEN.

Does Caselaw Access API access the network?

SKILL.md names 3 domains. In commands or code: api.case.law and case.law; the agent is likely to contact these when it follows the instructions. As links in the text: lil.law.harvard.edu. This is read from the text; nothing was executed.

Is Caselaw Access API safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Caselaw Access API use?

Caselaw Access API is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Caselaw Access API use?

About 1.1k tokens (SKILL.md is roughly 4.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Caselaw Access API?

Skills that share tags, products or a category with Caselaw Access API: Tw Legal RAG (aa0101181514/tw-legal-rag, 328 stars), Design Award Search (SeanJ1ang/design-judge-skills, 712 stars), China Lawyer Analyst (CSlawyer1985/china-lawyer-analyst, 196 stars) and Billing And Litigation Budget (THUYRan/Legal-Skills-Chinese, 874 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Caselaw Access API?

wentorai (a GitHub user) maintains it in wentorai/research-plugins, which has 298 GitHub stars. The repository holds 405 skills in this directory. The repository was last updated on June 19, 2026.

Source: wentorai/research-plugins on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.