DocketLayer

Federal and State Court Case Number Formats Explained

Resources  ·  Court Data

Every court case has a unique identifier, but the format of that identifier varies significantly between court types, jurisdictions, and sometimes individual courts. Passing the wrong format to the API returns a 422 error. This article explains the conventions you will encounter when working with federal, state, and Canadian courts.

Federal District Courts

Federal district court case numbers follow the pattern division:year-type-sequence. For example, 1:24-cv-09822 breaks down as:

  • 1 — division number. Multi-division districts like the Southern District of New York use this to identify which courthouse the case is assigned to. Single-courthouse districts omit it entirely.
  • 24 — the two-digit year the case was filed.
  • cv — case type: cv for civil, cr for criminal, mc for miscellaneous.
  • 09822 — the sequential number within that year and type.

When no division number is used, the format is 24-cv-00142. The division prefix is not standardized across courts — check the court's public portal to see whether a division number is part of the case number for that court.

Bankruptcy Courts

Bankruptcy case numbers follow the same year-type-sequence convention but always use bk as the type designator: 23-bk-11235. Chapter designations (7, 11, 13) are not part of the case number. Adversary proceedings within a bankruptcy case have their own number: 23-ap-00019. Query the main case number; adversary proceedings appear as related entries within the docket response.

Appellate Courts

Circuit court case numbers use a two-digit year followed by a sequential number: 24-1203. Because multiple circuits use the same format, the court code you pass to the API — ca2 for the Second Circuit, ca9 for the Ninth — disambiguates them. ACMS courts (Second and Ninth Circuits) use the same external numbering convention; the difference is in how DocketLayer accesses the underlying data, which is handled transparently.

State Court Case Numbers

State court case numbers have no single standard. Formats vary by state, court level, and county. Common patterns include:

  • California Superior Courts: 24STCV12345 — venue code, year, type designation, sequence.
  • New York Supreme Court: 100001/2024 — sequence number followed by year.
  • Florida Circuit Courts: 2024-CA-001234 — four-digit year, case type, sequence.
  • Illinois Circuit Courts: 2024-L-001234 — year, division code, sequence.

The most reliable source for the correct format is the court's own public portal — look up a known case to see exactly how that court formats its identifiers. The case_id_format field in the GET /v2/status response provides the expected pattern for every court in the registry.

Canadian Court File Numbers

Canadian courts use file numbers rather than case numbers. Federal court file numbers follow a structured format: the Federal Court uses T-NNNN-YY for trial matters (T-1045-24), A-NNNN-YY for appeals, and IMM-NNNN-YY for immigration proceedings. The Federal Court of Appeal uses A-NNNN-YY. The Tax Court uses year-based identifiers with type suffixes. Provincial court file number formats vary significantly by province and court level.

Using Case Numbers With the API

Pass the case number exactly as it appears on the court's public portal or official filed documents. Do not reformat, remove hyphens, change punctuation, or add leading zeros. The API validates the case_id against the known format for the specified court_code and returns a 422 if the format does not match. If you are unsure of the correct format for a specific court, query GET /v2/status and read the case_id_format field for that court.