Citation Verification API

Verify case law, statutes, regulations, and more against primary authority. Detect hallucinated citations, fabricated quotes, misstated holdings, and 40+ other error categories.

29M+ citations

40+ error categories

50 states + federal

~45s avg response

Schedule Demo → Get an API key in your first call

Authentication

Every request requires an API key in the x-api-key header. Keys are provisioned during onboarding.

curl https://api.counselstack.com/api/v1/check \
  -H "x-api-key: cs_live_..." \
  -H "Content-Type: application/json" \
  -d '{ ... }'

Keep your key secret. Do not expose it in client-side code. All requests must be made over HTTPS.

Base URL

Base https://api.counselstack.com

Check Citation

Verify a legal citation against primary authority. Returns an assessment, plain-language summary, and structured error labels.

POST/api/v1/check

Request Body

Parameter	Type	Description
citation_type required	string	Type of citation. See Citation Types.
citation_text required	string	The exact citation as it appears in the source document.
citation_context required	string	Surrounding sentence(s) showing how the citation is used. Include any parenthetical, quotation, or characterization.
jurisdiction_hint optional	string	Jurisdiction for disambiguation (e.g. `"CA"`, `"9th Cir."`). Useful for state statutes.

Example Request

curl -X POST https://api.counselstack.com/api/v1/check \
  -H "x-api-key: cs_live_..." \
  -H "Content-Type: application/json" \
  -d '{
  "citation_type": "case",
  "citation_text": "Dynamex Operations West, Inc. v. Superior Court, 4 Cal. 5th 903 (2018)",
  "citation_context": "Under the ABC test established in Dynamex, a worker is presumed to be an employee unless the hiring entity demonstrates three factors."
}'

Response

Field	Type	Description
analysis.overall_assessment	string	One of `correct`, `needs_improvement`, `incorrect`, `not_verifiable`
analysis.summary	string	Plain-language explanation of the verification result.
analysis.labels	ClientLabel[]	Structured error and treatment labels. See Error Labels.
usage.inputTokens	number	Total input tokens consumed.
usage.outputTokens	number	Total output tokens consumed.

Example Response

{
  "analysis": {
    "overall_assessment": "correct",
    "summary": "The citation accurately describes the ABC test established in Dynamex Operations West, Inc. v. Superior Court. The case adopted the ABC test for determining employee vs. independent contractor status under California wage orders. Note also that the California Legislature subsequently codified this test in Assembly Bill 5 (2019).",
    "labels": [
      { "code": "generally_followed" }
    ]
  },
  "usage": {
    "inputTokens": 28450,
    "outputTokens": 1842
  }
}

Check Balance

Returns remaining check credits for your API key.

GET/api/v1/balance

{
  "credits_remaining": 847,
  "plan": "prepaid"
}

Citation Types

The citation_type parameter routes the request to the appropriate verification pipeline.

Value	Authority	Example
case	Case Law	Dynamex Operations West, Inc. v. Superior Court, 4 Cal. 5th 903 (2018)
statute	Federal Statutes	42 U.S.C. § 1983
regulation	Federal Regulations	29 C.F.R. § 541.602(a)
state_statute	State Statutes	Cal. Lab. Code § 2775
constitution	State Constitutions	Cal. Const. art. I, § 1
fed_court_rule	Federal Court Rules	Fed. R. Civ. P. 12(b)(6)
fr	Federal Register	89 Fed. Reg. 32,842 (Apr. 26, 2024)
plaw	Public Laws	Pub. L. No. 117-169, 136 Stat. 1818

Coverage & Collections

Purpose-built legal data collections verified against primary authority.

case

Case Law

29M+ citations. Federal and state opinions with full text, citation graphs, parentheticals, and treatment history.

statute

Federal Statutes

United States Code. Full section text with hierarchy and cross-references.

regulation

Federal Regulations

Code of Federal Regulations via eCFR. Current and historical versions at section-level granularity.

state_statute

State Statutes

40+ state codes. Structured by jurisdiction with hierarchy, section text, and legislative history.

constitution

State Constitutions

All 50 states. Article, section, and clause-level text with amendment history.

fed_court_rule

Federal Court Rules

FRCP, FRE, FRAP, FRCrP, and Bankruptcy Rules with full text and hierarchical structure.

Federal Register

Final rules, proposed rules, and notices with full text and metadata.

plaw

Public Laws

Enacted legislation with Statutes at Large references and enrollment data.

Assessments

Every citation receives one of four assessments.

correct

Citation accurately represents the authority.

needs_improvement

Partially accurate but contains issues warranting review.

incorrect

Contains substantive errors — misstated holdings, fabricated quotes, or wrong authorities.

not_verifiable

Source text could not be retrieved. Manual review recommended.

Error Labels

Structured codes describing specific issues found during verification.

Citation Accuracy

Substantive Errors

holding_misstated

States a legal holding different from what the court decided

material_fact_error

A material fact of the case is wrong or fabricated

wrong_legal_standard

Applies an incorrect test or legal standard

outcome_misstated

The outcome or disposition is incorrect

holding_rationale_misstated

Outcome correct but reasoning misdescribed

overbroad_application

Extends holding beyond its stated limits

wrong_party_or_caption

Misidentifies the parties or case caption

procedural_posture_error

Misstates how the case reached the court

Quotation Errors

fabricated_quote

Quoted language does not appear in the source

quote_misinterpreted

Real quote used to support an incorrect proposition

Citation Metadata

case_name_mismatch

Case name does not match the resolved authority

case_name_partial_match

Case name partially matches but differs from canonical form

wrong_court

Deciding court is incorrectly identified

wrong_year

Decision year is incorrect

reporter_mismatch

Volume, reporter, or page does not match

pincite_out_of_range

Pinpoint citation falls outside the opinion's page range

Statutory & Regulatory

statutory_requirement_misstated

Statutory requirement or standard is misdescribed

cross_reference_ignored

A material cross-reference was not addressed

cross_ref_exception_overlooked

An exception via cross-reference was overlooked

Treatment

Treatment labels describe how subsequent courts have treated the cited authority. These are informational and do not affect the accuracy assessment.

generally_followed

Citing courts generally follow or apply the precedent favorably

distinguished_on_facts

Later courts distinguished on materially different facts

limited_by_courts

Holding has been narrowed or limited in scope

criticized_by_higher_court

A higher court has criticized the reasoning

overruled_or_abrogated

Overruled or abrogated by later authority

no_citing_cases

No citing cases found in the citation graph

Error Codes

200

Citation verified successfully.

400

Bad Request

Missing or invalid parameters.

401

Unauthorized

Missing or invalid API key.

402

Payment Required

No credits remaining.

429

Rate Limited

Too many requests.

500

Internal Error

Retry with exponential backoff.

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