# LexRails Legal Citation Checker

> LexRails Legal Citation Checker is a paid API for AI agents from lex.chainverdict.xyz, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-15).

Deterministically checks whether a legal citation is real or fabricated, returning a boolean validity result with attestation

## Facts

- Endpoint: GET https://lex.chainverdict.xyz/v1/cite/check
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/lexrails-legal-citation-checker-1b3a531f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RlUmaNwEj4g-D2ha9xMZ0

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability lexrails-legal-citation-checker-1b3a531f
```

Example prompt: Can you check whether this legal citation is real or fabricated: 'Brown v. Board of Education, 347 U.S. 483 (1954)'?

## When to prefer this

Choose LexRails when you need a deterministic, machine-verifiable check for legal citation authenticity — especially to guard against AI hallucination in legal documents, briefs, or research. Prefer this over LLM-based citation checks when you need an attestation artifact, auditability, or when cost-per-call micropricing via USDC is acceptable. Best suited for single-citation spot checks in automated legal workflows.

## Known failure modes

- Missing required 'q' parameter returns a 400-level error
- Ambiguous or malformed citation strings may produce indeterminate results
- Payment failure via x402 blocks access with a 402 response
- Network timeouts on the Base blockchain payment layer
- Unknown or highly obscure citations may return false negatives

## How this service works

Structural check of a single US case citation: catches impossible reporter volumes, unknown reporters, malformed patterns — the fabrication signals. Verdict: impossible / unknown-reporter / plausible.

## Output

Returns a JSON object containing a 'valid' boolean indicating whether the citation is real or fabricated, plus an '_attestation' object providing a cryptographic or structured attestation of the check result, along with any additional metadata fields

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "q"
     ],
     "properties": {
      "q": {
       "type": "string",
       "description": "US case citation to check structurally"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/lexrails-legal-citation-checker-1b3a531f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from lex.chainverdict.xyz](https://www.zero.xyz/host/lex.chainverdict.xyz/llms.txt)