Clerkmark · cover sheet · a LexHack 2026 entry

Spot likely fake case citations at intake.

Clerkmark reads a filed brief, looks up every case citation in a free law library, and writes a one-page memo. It tells a citation that is likely not a real case from one the library simply does not hold, and prints the rule behind each call.

[View the source] [How it works]
For
Court intake staff, self-help centres and pro se staff attorneys, at the moment a self-represented filing lands on the docket. The memo is written so the filer can read it too.
Why
2,079 court decisions on AI-hallucinated citations so far; 1,196 involve self-represented filers. Source: Damien Charlotin, AI Hallucination Cases database, as of 25 Sep 2026. Courts check each citation by hand today.
Not a database
A case database answers one lookup at a time. Clerkmark reads the whole filing, checks every citation and every quoted passage against the database, and writes up what it found.

How it works

  1. 1Reads the PDF and finds every case citation. The memo heading shows what was checked and how long it took.

    The memo heading for the synthetic sample filing, with a red CHECKED stamp that counts 23 citations.
    From the synthetic sample filing.

  2. 2Looks up each citation: which case sits at that volume and page, and whether the quoted words appear in the opinion. The reporter page is one click from the row.

    A memo row marked likely not a real case, with the reporter page open underneath showing that the cited page belongs to a different case.
    The cited page belongs to a different case.

  3. 3Writes the memo: each row sorted into a class, with the rule that decided it. A likely fake and a citation the library does not hold never look the same.

    Two memo rows: one circled in red and marked likely not a real case, the next underlined in pencil and marked not in the free library.
    Line 8 is likely not a real case. Line 9 is only outside the free library.

Measured

Twenty sample citations with known answers are scored on every run. Open the Evaluation tab for the current numbers.

Limits

United States case law only. Statutes, court rules, Id. and short-form citations are listed, not checked. Pin pages cannot be checked. The free library ends around 2019, so newer real cases read “Not in the free library”. A triage aid, not a finding.

Built with

eyecite and reporters_db (Free Law Project) · Caselaw Access Project free files (Harvard Library Innovation Lab) · FastAPI · pdfplumber · rapidfuzz · optional advisory by Google Gemini. The rule is deterministic; the model never changes a class.