# LexRails CFR Citation Validator

> LexRails CFR Citation Validator is a paid API for AI agents from lex.chainverdict.xyz, paid per call via x402, $0.009/call, status unknown (last checked 2026-09-14).

Validates whether a given Code of Federal Regulations (CFR) title citation is real and correctly formed, returning a deterministic true/false verdict

## Facts

- Endpoint: GET https://lex.chainverdict.xyz/v1/cfr/validate
- Price: $0.009/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/lexrails-cfr-citation-validator-cc6bba2e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_UwbUYBaxxWP2Sx-cRUDOq

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-cfr-citation-validator-cc6bba2e
```

Example prompt: Can you check whether '21 CFR Part 11' is a real, valid Code of Federal Regulations citation and not a hallucinated reference?

## When to prefer this

Choose this endpoint when you need a deterministic, paid-attestation check specifically for Code of Federal Regulations (CFR) citations — particularly in AI agent pipelines prone to hallucinating regulatory references. Prefer it over general web searches when you need a machine-verifiable boolean result with an attestation object suitable for audit trails, or when building automated guardrails that must flag fabricated CFR citations before they reach a human or published document.

## Known failure modes

- Missing required 'title' parameter returns an error response
- Ambiguous or malformed citation string may return valid:false even for real regulations
- Payment failure via x402 results in 402 response and no validation result
- Network timeout or service unavailability returns no result
- Non-CFR legal citation formats (e.g. U.S.C. sections) may not be supported

## How this service works

Validate a CFR citation structurally (title, part, section format).

## Output

A JSON object containing a 'valid' boolean indicating whether the provided CFR title citation is legitimate, plus an '_attestation' object providing a cryptographic or metadata proof of the check result for auditability.

## 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": [
      "title"
     ],
     "properties": {
      "title": {
       "type": "string",
       "description": "CFR title number (1-50)"
      }
     }
    }
   },
   "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-cfr-citation-validator-cc6bba2e/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)