# 2s.io US Court Opinion Search

> 2s.io US Court Opinion Search is a paid API for AI agents from 2s.io, paid per call via x402, $0.0036/call, status unknown (last checked 2026-09-13).

Search ~9 million US court opinions (SCOTUS, federal circuits, state appellate/supreme) by keyword, party name, citation, or docket number with court and date filters

## Facts

- Endpoint: GET https://2s.io/api/law/case-search
- Price: $0.0036/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/2s-io-861dda81
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_h20NSgx32Z9VDSmokx1aR

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 2s-io-861dda81
```

Example prompt: Search court opinions for cases about 'qualified immunity' in the 9th Circuit filed after 2018-01-01, sorted by citation count — show me up to 10 results.

## When to prefer this

Use this endpoint when you need to discover or find court opinions by keyword, party name, citation, or docket number across a broad corpus of ~9M US opinions. Prefer over manual CourtListener browsing when building automated legal research pipelines. Complements a case-verify endpoint when you need discovery first, then verification. Best when you need structured metadata (citations, court, year, snippet) rather than full opinion text.

## Known failure modes

- Query string too short (< 2 chars) or too long (> 500 chars) returns 400 validation error
- Invalid court slug pattern returns 400 error
- Invalid date format for filedAfter/filedBefore returns 400 error
- No matching opinions returns empty results array
- Payment failure (x402) returns 402 before executing search
- Rate limiting or upstream CourtListener unavailability returns 503

## How this service works

Search US court opinions (SCOTUS, federal circuits, state appellate/supreme — ~9M opinions). Query by free-text (party names, keywords, docket #, citation). Filter by court slug (e.g., "scotus", "ca9", "nysupct"), filing date range, and order (relevance/dateFiled-desc/dateFiled-asc/citeCount-desc). Returns clusterId, caseName, court, year, docket, reporter citations, citationCount, snippet, canonical URL. Discovery-side complement to case-verify. Backed by CourtListener (Free Law Project); underlying opinions are public domain.

## Output

Returns a list of matching court opinion records, each with a clusterId, caseName, court identifier, year, docket number, reporter citations, citationCount, a text snippet from the opinion, and a canonical CourtListener URL. Up to 20 results per call.

## Example request

```json
{
 "input": {
  "type": "http",
  "method": "GET",
  "queryParams": {
   "q": "artificial intelligence",
   "limit": 10,
   "order": "relevance"
  }
 }
}
```

## 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",
    "queryParams"
   ],
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "const": "GET"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "q"
     ],
     "properties": {
      "q": {
       "type": "string",
       "maxLength": 500,
       "minLength": 2
      },
      "court": {
       "type": "string"
      },
      "limit": {
       "type": "integer",
       "default": 10,
       "maximum": 20,
       "minimum": 1
      },
      "order": {
       "enum": [
        "relevance",
        "dateFiled-desc",
        "dateFiled-asc",
        "citeCount-desc"
       ],
       "type": "string"
      },
      "filedAfter": {
       "type": "string"
      },
      "filedBefore": {
       "type": "string"
      }
     },
     "additionalProperties": false
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/2s-io-861dda81/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 2s.io](https://www.zero.xyz/host/2s.io/llms.txt)