How to Search Federal and State Court Opinions with CourtListener

#legal #data #api #automation

CourtListener is a Free Law Project database of federal and state court opinions, oral arguments, and docket entries. It covers millions of decisions going back to the early 1900s, with full text search and a well-documented REST API. For legal research, litigation support, and compliance monitoring at scale, it is one of the most useful public legal datasets available.

Why automate this?

Manual legal research through Westlaw or LexisNexis is expensive. CourtListener provides much of the same underlying case data for free. Automating access matters when:

Litigation research -- pulling all circuit court opinions that cite a specific statute or case
Compliance monitoring -- tracking new decisions in a regulatory area on a weekly schedule
Academic and policy research -- building datasets of opinions across a jurisdiction, time range, or judge
Law firm business development -- identifying active cases in a practice area for targeted outreach
Expert witness work -- finding cases where a specific expert has testified

The CourtListener web interface is good for ad hoc lookups. It is not designed for bulk export or scheduled pulls.

How CourtListener is structured

CourtListener separates opinions (the text of court decisions) from dockets (the procedural record of a case). For most research purposes, opinions are the primary resource. Each opinion is linked to a cluster (a single case decision, which may have multiple opinion documents -- majority, concurrence, dissent) and a docket.

The API supports full text search with filters for court, date range, judge, citation, and status (published, unpublished, etc.).

What data you get

Each record in the output includes:

case_name -- full case name
court -- court identifier (e.g., ca9 for the Ninth Circuit)
date_filed -- decision date
citations -- list of citation strings (e.g., "123 F.3d 456")
judges -- authoring and participating judges
precedential_status -- published, unpublished, errata, etc.
plain_text -- full opinion text (where available)
absolute_url -- direct link to CourtListener opinion page
download_url -- link to PDF where available

Running a search

The CourtListener Legal Opinions actor on Apify accepts a keyword query, court filter, and date range. It queries the CourtListener API, handles pagination, and returns normalized records.

Example input:

{
  "query": "securities fraud materiality",
  "court": "ca2",
  "dateFrom": "2020-01-01",
  "maxResults": 100
}

Output is available as JSON or CSV.

Practical workflow

For a weekly compliance newsletter: schedule the actor with a topic query and the past 7 days as the date window. Pull new opinions, extract case names and citations, and pipe them into a summary template.

For a case dataset: run with a specific court and a multi-year date range. The full text field makes the output suitable for NLP analysis.