Legal citation and quotation verifier (US case law)

Extracts US reporter citations from a brief (U.S., S. Ct., L. Ed., F., F.2d, F.3d, F.4th, F. Supp., state and regional reporters) and checks each against Harvard's Caselaw Access Project and, when the operator has configured a token, the CourtListener Citation Lookup API. Reports FOUND, MISMATCH (case name, year or circuit differs), NOT_FOUND, AMBIGUOUS, or UNCHECKED with the reason, and never marks an unchecked citation FOUND. Quotations are searched in the cited opinion with deterministic matching and every normalization is listed. Statutes, id., supra and Westlaw/Lexis cites are reported as UNCHECKABLE_TYPE. Without a CourtListener token the result is partial for volumes outside CAP (roughly pre-2019). The optional proposition check is off by default and can only point at a verified passage. Not legal advice.

Every result is a signed, verifiable answer:

• a W3C Verifiable Credential 2.0, signed with eddsa-jcs-2022 by did:web:agents.writerslogic.com;
• a C2PA-style manifest that lists every source the agent read, each with its SHA-256;
• an EIP-191 co-signature over the same digest.

Change one byte and verification fails, so you can pass the result to a client, an auditor or another agent and they can check it without trusting you or us.

How to use Legal citation and quotation verifier (US case law)

1. Fill in the input form. Required fields are marked; the form opens with a working example.
2. Start the run.
3. Read the result in the Output tab, or download the dataset as JSON. The full signed envelope is also saved as the OUTPUT record in the key-value store.

Input

Field	Required	Description
text	no	Brief or memo text. Citations and their case names, court and year are extracted from it.
citations	no	Citations to check instead of, or in addition to, text.
quotes	no	Quotations to find verbatim in the cited opinion.
check_propositions	no	Default false. Runs one optional model call that may only point at a verified passage.
propositions	no
max_citations	no	Distinct reporter citations to check. Default 40.

Example input:

{
  "text": "Plaintiff's position follows from Brown v. Board of Education, 347 U.S. 483, 495 (1954) (\"Separate educational facilities are inherently unequal.\"). Defendant's liability under the Montreal Convention is established by Varghese v. China Southern Airlines Co., Ltd., 925 F.3d 1339 (11th Cir. 2019).",
  "quotes": [
    {
      "citation": "347 U.S. 483",
      "quote": "Separate educational facilities are inherently unequal."
    }
  ]
}

Output

{
  "agent": "legal-cite-verifier",
  "priceUsd": 1.88,
  "data": { "...": "the agent's answer" },
  "_provenance": { "credential": {}, "manifest": {}, "ethSignature": "0x..." }
}

To check a result for free, POST { "data": ..., "_provenance": ... } to https://agents.writerslogic.com/api/v1/verify-provenance, or verify it offline against the public key in the DID document.

Pricing

$1.88 per successful run, charged once and only after the agent returns its answer. If the input is rejected or the agent fails, you are not charged for the call.

Use it from code or an AI assistant

• Apify API and integrations: call this Actor from Make, Zapier, n8n, LangChain or the Apify API like any other Actor.
• MCP: npx -y @writerslogic/ai-agents-mcp exposes this agent and the rest of the hub as tools.
• x402: the same agent is available at POST https://agents.writerslogic.com/api/v1/legal-cite-verifier, paid per call in USDC on Base.

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FAQ

Who runs this? WritersLogic. The agent runs on the WritersLogic Verifiable AI Agent Hub; this Actor sends your input there and returns the signed result.

Is my input stored? The Actor stores your result in your own Apify storage. Ask before sending confidential documents; the hub is a third-party service from your point of view.