validate CNJ case number check digit
The 2 digits right after the case number's first 7 digits are not arbitrary: they come from a division by 97 over the rest of the number, and a single swapped digit anywhere in the middle already breaks the math.
The division by 97 over NNNNNNN 0000001, year 2024, segment 8 and court 26 lands exactly on remainder 59, and 98 minus 59 gives the 39 check digit shown.
Only the OOOO field changed from 0100 to 0110, but that alone rearranges the whole division by 97 and produces a different remainder, proof that the DV depends on all 5 fields together, not just NNNNNNN.
In segment 3 (STJ), the TR field is always 00, because there is no lower court beneath a superior court, but it still enters the DV calculation as two zeros.
The result of the mod-97 algorithm (same as IBAN) applied to the full number without the DD. Two digits ensure integrity.
No. Since the check digit is always 98 minus a remainder from division by 97, and that remainder ranges from 0 to 96, the result stays between 2 and 98. A CNJ number with DD equal to 00 or 01 is already formally wrong, without even finishing the calculation.
Yes, and it is common: NNNNNNN alone does not identify the case, only the full combination with year, segment, court and origin does that. That is why the check digit calculation includes those other 4 fields, not just the sequential number.
No. The check digit only proves the 20 digits are internally consistent with each other, a math check against typos. Confirming the case actually exists and is active requires querying the court or a database like DataJud, which pulls data straight from the courts' own systems.
Informational tool. A formally valid number does not guarantee that the case exists or is active.