| name | caselaw-access-api |
| description | Query 360+ years of US case law via the Harvard Caselaw Access Project |
| metadata | {"openclaw":{"emoji":"⚖️","category":"domains","subcategory":"law","keywords":["case law","legal database","court opinions","Harvard law","judicial data","legal research"],"source":"https://case.law/"}} |
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
curl "https://api.case.law/v1/cases/?search=free+speech&decision_date_min=2020-01-01"
curl "https://api.case.law/v1/cases/12345678/"
curl "https://api.case.law/v1/cases/?jurisdiction=us&court=us-sup-ct&search=miranda+rights"
curl "https://api.case.law/v1/cases/?decision_date_min=2015-01-01&decision_date_max=2025-12-31"
curl -H "Authorization: Token YOUR_API_KEY" \
"https://api.case.law/v1/cases/12345678/?full_case=true"
Query Parameters
| Parameter | Description | Example |
|---|
search | Full-text search | search=due+process |
jurisdiction | Filter by jurisdiction slug | jurisdiction=cal (California) |
court | Filter by court slug | court=us-sup-ct |
decision_date_min | Earliest date | decision_date_min=2020-01-01 |
decision_date_max | Latest date | decision_date_max=2025-12-31 |
cite | Search by citation | cite=410+U.S.+113 |
name_abbreviation | Case name | name_abbreviation=Roe+v.+Wade |
ordering | Sort results | ordering=-decision_date |
page_size | Results per page (max 100) | page_size=50 |
full_case | Include full text | full_case=true |
Courts and Jurisdictions
curl "https://api.case.law/v1/courts/"
curl "https://api.case.law/v1/jurisdictions/"
curl "https://api.case.law/v1/reporters/"
Python Usage
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
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:
Key Jurisdictions
| Slug | Jurisdiction | Cases |
|---|
us | Federal (all) | ~1.5M |
us-sup-ct | US Supreme Court | ~65K |
cal | California | ~500K |
ny | New York | ~600K |
tex | Texas | ~300K |
ill | Illinois | ~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