Each authority a brief cites is checked against a stated corpus of case law: does the opinion exist, is it the case the brief names, and is each quotation in it, byte for byte.
The problem
A filer presenting a brief to a federal court certifies, after an inquiry reasonable under the circumstances, that its legal contentions are warranted by existing law (Federal Rule of Civil Procedure 11(b)).
Courts have sanctioned filers whose briefs cited opinions that do not exist. In 2023 a federal court in New York imposed sanctions for such a brief, and in 2024 a federal court of appeals referred a lawyer for discipline for citing a case that could not be found.
A cite check asks the same questions of every citation: is it real, is it the case named, does the quotation appear in it, and does the pinpoint page fall inside it.
Recorded outputOne certify call on a constructed brief: fictitious parties and a fictitious district, citing real opinions of the United States Supreme Court, one invented citation, and one real citation under an invented name. The corpus is the declared case-law corpus of 471,479 opinions as of 2019-09-09. No AI engine was configured.
Three catches
A citation that does not exist
411 U.S. 9999 (1973), cited as Ostrander v. Vellacott.
not_located
no opinion matching this citation was located in the corpus searched (cap-static-us1-572-f3d1-935, 471,479 opinions, as of 2019-09-09).
A real citation that resolves to a different case
424 U.S. 319, 335 (1976) is a real citation. The brief calls it Whitlock v. Farraday.
resolvedcites_different_case
the brief names "Whitlock v. Farraday"; the opinion the corpus holds at 424 U.S. 319 is "Mathews v. Eldridge", and the two captions share no distinctive party name.
A quotation that is not in the opinion
Tinker v. Des Moines Independent Community School District, 393 U.S. 503, 506 (1969), quoted as:
It can hardly be argued that either students or teachers shed their constitutional rights to freedom of speech or association at the schoolhouse gate.
resolvedname_matchesquote_not_found
no part of this quotation was located in the held opinion. The first 114 of its 150 characters do appear there, and then the brief reads "association at the schoolhouse gate." where the opinion reads "expression at the schoolhouse gate. This has been the unmist". ⚠ THE HELD CORPUS IS OCR'd FROM BOUND VOLUMES and a character it misread is a difference this check cannot tell from a misquotation
Every citation, every verdict
POST /api/tenants/{tenant}/certify?reportType=brief-citation-check&filename=brief.txt
Goss v. Lopez, 419 U.S. 565, 576 (1975)resolvedname_matchesquote_verified
Check how this was answered
existence resolved: located in the corpus searched (cap-static-us1-572-f3d1-935, as of 2019-09-09)
the corpus holds Goss v. Lopez, 419 U.S. 565 (1975-01-22)
identity name_matches: the two captions share goss, lopez
quotation quote_verified: found byte-exact in the held opinion at offset 13972 after the declared normalisation (whitespace and typographic quotes only)
pinpoint pinpoint_within_case: page 576 lies within 565–600, the span the reporter printed for this opinion
Source the brief, as filed
The Supreme Court has decided this question for suspensions of exactly this length. A suspension of up to ten days, the Court said, "is a serious event in the life of the suspended child." Goss v. Lopez, 419 U.S. 565, 576 (1975). That is why the student must be told what she is accused of and given a chance to answer before she is sent home.
the brief, at character 1017
Tinker v. Des Moines Independent Community School District, 393 U.S. 503, 506 (1969)resolvedname_matchesquote_not_found
Check how this was answered
existence resolved: located in the corpus searched (cap-static-us1-572-f3d1-935, as of 2019-09-09)
the corpus holds Tinker v. Des Moines Independent Community School District, 393 U.S. 503 (1969-02-24)
identity name_matches: the two captions share tinker, moines, independent, community, school, district
quotation quote_not_found: no part of this quotation was located in the held opinion. The first 114 of its 150 characters do appear there, and then the brief reads "association at the schoolhouse gate." where the opinion reads "expression at the schoolhouse gate. This has been the unmist". ⚠ THE HELD CORPUS IS OCR'd FROM BOUND VOLUMES and a character it misread is a difference this check cannot tell from a misquotation
pinpoint pinpoint_within_case: page 506 lies within 503–526, the span the reporter printed for this opinion
Source the brief, as filed
The Board answers that discipline inside a school is a matter for the school alone. That is not the law. The Constitution does not stop at the classroom door. See Tinker v. Des Moines Independent Community School District, 393 U.S. 503, 506 (1969) ("It can hardly be argued that either students or teachers shed their constitutional rights to freedom of speech or association at the schoolhouse gate.").
the brief, at character 1381
Whitlock v. Farraday, 424 U.S. 319, 335 (1976)resolvedcites_different_caseno_quote_in_brief
Check how this was answered
existence resolved: located in the corpus searched (cap-static-us1-572-f3d1-935, as of 2019-09-09)
the corpus holds Mathews v. Eldridge, 424 U.S. 319 (1976-02-24)
identity cites_different_case: the brief names "Whitlock v. Farraday"; the opinion the corpus holds at 424 U.S. 319 is "Mathews v. Eldridge", and the two captions share no distinctive party name
quotation no_quote_in_brief: no quotation is attached to this citation
pinpoint pinpoint_within_case: page 335 lies within 319–350, the span the reporter printed for this opinion
Source the brief, as filed
As explained in Whitlock v. Farraday, 424 U.S. 319, 335 (1976), the process that is due depends on the private interest affected, the risk of an erroneous deprivation under the procedures used, and the interest of the government. Each factor favors the student. Nine days of lost instruction cannot be given back, a short conversation before the suspension would have cost the school almost nothing, and the Board has identified no emergency. See Ostrander v. Vellacott, 411 U.S. 9999 (1973).
the brief, at character 1649
Ostrander v. Vellacott, 411 U.S. 9999 (1973)not_locatedno_resolved_caseno_quote_in_brief
Check how this was answered
existence not_located: no opinion matching this citation was located in the corpus searched (cap-static-us1-572-f3d1-935, 471,479 opinions, as of 2019-09-09)
identity no_resolved_case: no opinion resolved, so there is no reported case name to compare against
quotation no_quote_in_brief: no quotation is attached to this citation
pinpoint no_pincite: this citation names no pinpoint page
Source the brief, as filed
As explained in Whitlock v. Farraday, 424 U.S. 319, 335 (1976), the process that is due depends on the private interest affected, the risk of an erroneous deprivation under the procedures used, and the interest of the government. Each factor favors the student. Nine days of lost instruction cannot be given back, a short conversation before the suspension would have cost the school almost nothing, and the Board has identified no emergency. See Ostrander v. Vellacott, 411 U.S. 9999 (1973).
the brief, at character 2082
Ingraham v. Wright, 430 U.S. 651 (1977)resolvedname_matchesno_quote_in_brief
Check how this was answered
existence resolved: located in the corpus searched (cap-static-us1-572-f3d1-935, as of 2019-09-09)
the corpus holds Ingraham v. Wright, 430 U.S. 651 (1977-04-19)
identity name_matches: the two captions share ingraham, wright
quotation no_quote_in_brief: no quotation is attached to this citation
pinpoint no_pincite: this citation names no pinpoint page
Source the brief, as filed
The Board relies on the rule that corporal punishment may be imposed without a prior hearing. See Ingraham v. Wright, 430 U.S. 651 (1977). That rule concerns a different sanction and does not reach an exclusion from school.
the brief, at character 2223
Corpus
cap-static-us1-572-f3d1-935
Opinions held
471,479
As of
2019-09-09
Reporters held
F.3d volumes 1 to 935; U.S. volumes 1 to 572
Boundary
CERTIFIED: this report states, for each citation it could read, whether an opinion matching it was located in the stated corpus, whether the case name the brief gives matches the one that corpus records, and - for the part of that corpus whose opinion text is held - whether quoted language appears in it. Coverage differs by verdict class and this report states which class was answered against what.
NOT ATTESTED
That a citation supports the proposition it is offered for is not attested.
The treatment or current validity of any case is not attested, including whether it was later reversed, overruled or superseded.
This report consults no citator.
That a citation reported as not located is absent from the law is not attested; it is a statement about the corpus searched and its stated date.
Where the corpus searched carries the index for a reporter and its opinion text is outside the text held, a quotation is reported unverifiable in that corpus by name, which is a statement about our holdings and never a finding against this document.
"Not located" is a statement about the stated corpus. It is not a statement that no such opinion exists anywhere, and the certificate does not make it.
Check it without Factum
The certificate is published as it was returned. Download it with the key and the Factum Verifier, and run the command. It needs Node 18 or later and nothing else.
VERIFIED
keyId vd-2b223ab58835e187
canonical bytes 23070
barcode … (the signed barcode, 465 characters, printed in full when you run it)
surface FULL - the body carries no surface block, so every claim the run captured is on it
CERTIFIED BY THIS CHECK: this document was signed by the holder of the private half of the
key you supplied, over the canonical form named in its signature block, and has not been
altered by one byte since.
NOT CERTIFIED BY THIS CHECK: that the key you supplied is the operator's. That comes from
WHERE YOU OBTAINED THE KEY and from nothing in this file - a valid signature under the wrong
key is exactly what a forgery looks like.