# legal_fetch_patent_citations

Fetch forward and backward citation chains for a specific patent. Read-only. No side effects. Idempotent. patent_number: Patent number in EPODOC format e.g. EP1000000 for European, CN120586032 for Chinese, JP2020123456 for Japanese, WO2020123456 for PCT, US10000000 for US. Required. jurisdiction: Optional hint — one of EP, US, WO, CN, JP, KR, etc. Default EP. The tool normalises the patent number automatically; passing CN120586032 with jurisdiction EP is valid. Returns citing patents (forward citations) and cited patents (backward citations) with filing dates and titles. Use this when building a prior art citation chain for a specific patent you already have. Use legal_search_patents_by_keyword instead when you need to find patents by topic not by citation. Verified source: EPO OPS. 24-hour cache. If this tool's response does not serve the user's need, call report_feedback with feedback_type="agent_gap", tool_id="legal_fetch_patent_citations", intended_query="{what the user needed}", gap_description="{what was missing or wrong in the result}".

Agent View of the PolicyLayer registry record for `legal_fetch_patent_citations`. HTML page: https://policylayer.com/tools/dev-7bd0-mcp-server/legal-fetch-patent-citations

## Facts

- Tool: `legal_fetch_patent_citations`
- Server: DataNexus MCP (`dev-7bd0/mcp-server`) — https://policylayer.com/tools/dev-7bd0-mcp-server.md
- Homepage: https://github.com/dev-7bd0/mcp-server
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 2
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `jurisdiction` | string | no | Patent office code: EP, US, WO. Default EP. Optional. |
| `patent_number` | string | no | Patent number e.g. EP3456789 or US10123456. Required. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "legal_fetch_patent_citations",
    "arguments": {}
  }
}
```

## Why legal_fetch_patent_citations is rated Low

This tool performs passive data retrieval of patent citation metadata from public patent databases. It retrieves existing information about patent relationships without creating, modifying, deleting, or executing any operations. The explicit "read-only" and "idempotent" designations confirm no side effects are possible.

From the tool's own definition: "Tool description explicitly states: 'Read-only. No side effects. Idempotent.' Functionality is to 'Fetch forward and backward citation chains for a specific patent' and 'Returns citing patents (forward patents) and cited patents (backward citations) with…"

## Use case

AI agents call legal_fetch_patent_citations to retrieve information from DataNexus MCP without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches DataNexus MCP:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "legal_fetch_patent_citations": {}
  }
}
```

## Other tools on DataNexus MCP (54)

- `apikeys_revoke_api_key` — Destructive — https://policylayer.com/tools/dev-7bd0-mcp-server/apikeys-revoke-api-key.md
- `apikeys_rotate_api_key` — Destructive — https://policylayer.com/tools/dev-7bd0-mcp-server/apikeys-rotate-api-key.md
- `compliance_check_sam_exclusion` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/compliance-check-sam-exclusion.md
- `compliance_fetch_finra_broker` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/compliance-fetch-finra-broker.md
- `compliance_fetch_npi_provider` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/compliance-fetch-npi-provider.md
- `compliance_search_npi_by_name` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/compliance-search-npi-by-name.md
- `domain_check_email_security` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-check-email-security.md
- `domain_fetch_dns_records` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-fetch-dns-records.md
- `domain_fetch_domain_history` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-fetch-domain-history.md
- `domain_fetch_domain_rdap` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-fetch-domain-rdap.md
- `domain_fetch_reverse_ip` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-fetch-reverse-ip.md
- `domain_fetch_ssl_certificate_chain` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-fetch-ssl-certificate-chain.md
- `domain_fetch_subdomains` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/domain-fetch-subdomains.md
- `frontend_security_audit_ci_pipeline` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/frontend-security-audit-ci-pipeline.md
- `frontend_security_audit_manifest` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/frontend-security-audit-manifest.md
- `frontend_security_detect_typosquatting` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/frontend-security-detect-typosquatting.md
- `frontend_security_fetch_package_risk_brief` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/frontend-security-fetch-package-risk-brief.md
- `govcon_fetch_open_solicitations` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/govcon-fetch-open-solicitations.md
- `govcon_fetch_vendor_contract_history` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/govcon-fetch-vendor-contract-history.md
- `govcon_search_contract_awards` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/govcon-search-contract-awards.md
- `legal_fetch_inventor_portfolio` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/legal-fetch-inventor-portfolio.md
- `legal_fetch_patent_by_number` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/legal-fetch-patent-by-number.md
- `legal_search_patents_by_keyword` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/legal-search-patents-by-keyword.md
- `nonprofit_fetch_charity_uk` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/nonprofit-fetch-charity-uk.md
- `nonprofit_fetch_nonprofit_by_ein` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/nonprofit-fetch-nonprofit-by-ein.md
- `nonprofit_fetch_nonprofit_financial_trends` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/nonprofit-fetch-nonprofit-financial-trends.md
- `nonprofit_fetch_nonprofit_full_profile` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/nonprofit-fetch-nonprofit-full-profile.md
- `nonprofit_search_nonprofits_by_category` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/nonprofit-search-nonprofits-by-category.md
- `nonprofit_search_nonprofits_by_name` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/nonprofit-search-nonprofits-by-name.md
- `regulatory_fetch_docket_details` — Read — https://policylayer.com/tools/dev-7bd0-mcp-server/regulatory-fetch-docket-details.md
- …and 24 more: https://policylayer.com/tools/dev-7bd0-mcp-server.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=dev-7bd0-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/dev-7bd0-mcp-server