Legal Case Law and Regulation Search

Legal Case Law and Regulation Search

Search US case law via CourtListener and Harvard Case Law Access Project, and EU law via EUR-Lex. Covers court opinions, dockets, and legislative documents.

CourtListener API (US Case Law)

Free, open API for US federal and state court opinions and dockets. Base URL: https://www.courtlistener.com/api/rest/v4/

Search Opinions

curl -s "https://www.courtlistener.com/api/rest/v4/search/?q=qualified+immunity&type=o&order_by=score+desc" \
  | python3 -c "
import sys, json
data = json.load(sys.stdin)
for r in data.get('results', [])[:10]:
    name = r.get('caseName', 'N/A')
    court = r.get('court', 'N/A')
    date = r.get('dateFiled', 'N/A')
    cite = r.get('citation', [r.get('sibling_ids', 'N/A')])
    print(f'[{date}] {name}')
    print(f'  Court: {court}')
    print()
"

Search Dockets

curl -s "https://www.courtlistener.com/api/rest/v4/search/?q=antitrust+merger&type=r&order_by=score+desc"

Filter by Date Range

curl -s "https://www.courtlistener.com/api/rest/v4/search/?q=fourth+amendment+digital+privacy&type=o&filed_after=2020-01-01&filed_before=2024-12-31&order_by=dateFiled+desc"

Filter by Court

# Supreme Court opinions
curl -s "https://www.courtlistener.com/api/rest/v4/search/?q=free+speech&type=o&court=scotus&order_by=dateFiled+desc"

# Specific circuit court
curl -s "https://www.courtlistener.com/api/rest/v4/search/?q=patent+eligibility&type=o&court=cafc&order_by=dateFiled+desc"

Common Court Codes

scotus (SCOTUS), ca1-ca11 (Circuit Courts), cafc (Federal Circuit), cadc (DC Circuit), nyd (SDNY), cand (N.D. Cal).

Harvard Case Law Access Project

Historical US case law (1658-2020). Free API with registration. Base URL: https://api.case.law/v1/

Search Cases

curl -s "https://api.case.law/v1/cases/?search=miranda+rights&decision_date_min=2000-01-01&page_size=10" \
  | python3 -c "
import sys, json
data = json.load(sys.stdin)
for c in data.get('results', []):
    name = c.get('name_abbreviation', 'N/A')
    date = c.get('decision_date', 'N/A')
    court = c.get('court', {}).get('name', 'N/A')
    cite = c.get('citations', [{}])[0].get('cite', 'N/A') if c.get('citations') else 'N/A'
    print(f'[{date}] {name}')
    print(f'  Citation: {cite}  Court: {court}\n')
"

Search by Citation

curl -s "https://api.case.law/v1/cases/?cite=410+U.S.+113"

Filter by Jurisdiction

curl -s "https://api.case.law/v1/cases/?search=eminent+domain&jurisdiction=cal&decision_date_min=2010-01-01&page_size=10"

EUR-Lex (EU Law)

Access EU legislation, case law, and treaties via the EUR-Lex SPARQL endpoint.

Search EU Legislation via SPARQL

curl -s -G "https://eur-lex.europa.eu/EURLexWebService" \
  --data-urlencode "query=SELECT ?doc ?title WHERE {
    ?doc a <http://publications.europa.eu/ontology/cdm#regulation> ;
         <http://publications.europa.eu/ontology/cdm#resource_legal_title> ?title .
    FILTER(CONTAINS(LCASE(?title), 'artificial intelligence'))
  } LIMIT 10" \
  --data-urlencode "format=application/sparql-results+json"

Lookup by CELEX Number

curl -s "https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32016R0679" -o gdpr.html

Best Practices

1. Use CourtListener for recent US case law; it has the most up-to-date coverage.
2. Use Harvard Case Law for historical cases and bulk data access.
3. CourtListener requires no API key for basic search; register for higher rate limits.
4. Always include date filters to narrow results for broad legal topics.
5. For citation lookups, normalize to standard reporter format (e.g., "410 U.S. 113").
6. EUR-Lex SPARQL queries can be complex; start with keyword REST search first.
7. Never provide legal advice; present search results as reference material only.