Federal court case number format, decoded.

How a federal case number is built

A federal district court case number looks like a code but it is just four fields in a fixed order, and sometimes one or two more at the end. Every court that publishes a guide describes the same skeleton: where in the court the case sits, the year it was opened, what kind of case it is, and a running count.

The first digit is local, not national

The most common mistake is to treat the first digit as a standard code. It is not. Each district assigns its own office or division digits, so the same digit means different places in different courts. Two districts that published their lists show how far they diverge.

That is why this decoder tells you the digit but never names a place. The District of Oregon, for one, refers readers to its own local rule (LR 3-2) for its list, which is the right instinct: ask or read the court that issued the number.

Case type codes

The Southern District of New York is a useful reminder that not every code is available everywhere: its opening-codes manual says that for civil case filing only the type code "cv" is available. Courts may also use codes we could not confirm from an official page; the decoder labels those as not in the sourced list rather than guessing.

Worked example (hypothetical)

Suppose a filing is captioned 1:23-cv-00123-ABC. The office digit is 1, which you cannot translate without the court. The year is 23, so filed in 2023 (two digits cannot tell 2023 from 1923, so the decoder reads 00 to 26 as 20xx and 27 to 99 as 19xx). cv means civil. 00123 is the sequence, equal to 123. ABC is the assigned judge. Now compare 1-25-cr-12345-SAB-1: a criminal case from 2025, sequence 12345, judge SAB, and defendant number 1. The decoder gives the same breakdown for any number in these shapes, and says so when a suffix does not fit.

Edge cases and common mistakes

• Dropping the judge initials. The District of Oregon says that when calling the clerk about an active case, it is essential to give the complete number including the judge initials.
• Treating the sequence as a count of all cases. It runs by type and, in the districts that say so, restarts each year, so civil and criminal sequences are independent.
• Punctuation. Some courts show a colon after the office digit (1:23-cv-00123) and others hyphens (1-25-cr-12345-SAB-1). The decoder accepts both.
• Mixing up district and appeals numbers. This decoder is for the district-court style only; appellate case numbers are not covered.

Who this is for

Paralegals, journalists, researchers and anyone handed a docket number who wants to know what each piece says before asking the clerk or searching PACER.

What this does not cover

The decoder reads format only. It does not tell you which court issued a number, whether a case exists, who the parties are or how the case stands, and it never contacts PACER or any court. It does not cover appellate numbers, state court docket numbers, tribal courts or the Court of International Trade. Only the districts named in the Sources were read, so a district with its own variation may differ from what is shown. For bankruptcy numbers use the bankruptcy case number decoder, and for the civil cover sheet's three-digit codes see the JS 44 nature of suit code list.

FAQ

What is the format of a federal court case number?

Most federal district courts write it as office, year, case type and sequence, for example 1:23-cv-00123, and then add the initials of the assigned judge. The one-digit office or division code, the two-digit year, the case type letters and the sequence number come from the court's case management system. Punctuation and number of digits differ between courts.

What does cv mean in a federal case number?

cv marks a civil case. The district court guides we read pair it with cr for criminal, mc for miscellaneous, po for petty offense and mj for magistrate judge matters. Bankruptcy courts use bk for a bankruptcy case and ap for an adversary proceeding.

What does 1:23-cv-00123 mean?

Read in the usual order: office or division 1, filed in 2023 (the year is two digits), a civil case, and the 123rd civil sequence number. What office 1 means depends on the court, and the number does not say which court. Eastern District of Washington uses 1 for Spokane, while the District of South Carolina uses 1 for Aiken.

What do the letters at the end of a federal case number mean?

They are the initials of the judge assigned to the case. The District of South Carolina says a second set of initials after the district judge's signals assignment of all or part of the case to a magistrate judge. The District of Oregon adds its two-letter judge code once a judge is assigned and asks callers to give the full number including those initials.

Do the leading zeros in the sequence number matter?

Usually they are formatting. The Eastern District of Washington page says no leading zeros are required but the system accepts them, though its own validation pattern says the number cannot start with 0. If a filing system rejects your number, ask that court's clerk which form it wants.

What is the defendant number at the end of a criminal case number?

In criminal cases some courts add a hyphen and a number for each defendant. The District of South Carolina shows 01, 02 and so on; the Eastern District of Washington shows a single digit, as in 1-25-cr-12345-SAB-1. Civil numbers do not carry it.

Does the case number tell me which court the case is in?

No. None of the district guides we read put the court name in the number, so the same 1:23-cv-00123 can exist in many districts. You need the court as well as the number to find a docket.

How do I look up a federal case once I have the number?

Use PACER. Registered users can search a specific court for the case or use the PACER Case Locator, a nationwide index of federal cases. This page decodes the format only and does not look up any case.

Sources

Retrieved 2026-10-20. Each link was opened and the statement next to it was checked against the text.

• U.S. District Court, Eastern District of Washington: case number format
• U.S. District Court, District of South Carolina: case number format
• U.S. District Court, District of Oregon: the court's case numbering system (CM/ECF user manual)
• U.S. District Court, Southern District of New York: Civil Statistical Case Opening Codes Manual (May 12, 2015)
• U.S. Bankruptcy Court, Central District of California: The Central Guide, Supplement 9004-1 (August 2022)
• PACER: Public Access to Court Electronic Records