Cryptographic attorney attestation for AI-generated legal output.
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Upload or paste a document to check if an attorney has attested to it.
LegalSeal is an open-source cryptographic attestation protocol that creates verifiable proof when a licensed attorney reviews an AI-generated legal document. As courts increasingly sanction lawyers for filing unverified AI output, LegalSeal provides the missing standard for documenting human review of AI-generated legal work.
The protocol works by generating a SHA-256 hash of the document content, binding it to the reviewing attorney's bar number, jurisdiction, and attestation statement, and producing a tamper-proof verification receipt. The original document is never stored — only its cryptographic fingerprint. If even a single character of the document changes after attestation, the hash will no longer match, making any post-review modification immediately detectable.
LegalSeal addresses the accountability gap created by AI legal tools like Harvey, CoCounsel, and ChatGPT. While these tools can draft contracts, motions, and briefs in seconds, there has been no standard way to prove that a human attorney actually reviewed the output before it left the firm. LegalSeal fills that gap.
LegalSeal uses the same SHA-256 cryptographic hashing used in digital signatures, blockchain, and secure communications. Here is how the attestation process works:
Over 716 lawyers have faced sanctions, fines, or disciplinary action for filing AI-generated documents that contained fabricated case citations, hallucinated legal reasoning, or unverified factual claims. The most notable case — Mata v. Avianca (S.D.N.Y. 2023) — resulted in sanctions after an attorney submitted a ChatGPT-generated brief containing six fictitious case citations.
Since then, courts across the country have implemented AI disclosure requirements. Multiple federal districts and state bars now require attorneys to certify that they have verified any AI-assisted work product. The ABA's Formal Opinion 512 (2024) confirmed that lawyers have an ethical obligation to review AI-generated output before submission.
Yet until LegalSeal, there was no technical standard for proving that review actually happened. A verbal assertion of "I reviewed it" offers no verifiable evidence. LegalSeal transforms that assertion into a cryptographic proof — a timestamped, hash-linked attestation tied to a specific document and a specific attorney's bar number.
Sanctions for unverified AI legal work range from monetary fines to case dismissal to bar disciplinary proceedings. In Park v. Kim (2024), attorneys faced $5,000 sanctions for AI hallucinations. In Ex parte Lee, a Texas court required attorneys to certify AI non-use or verify all citations. The pattern is clear: courts are treating unverified AI output as a violation of Rule 11 (Federal) and corresponding state rules requiring reasonable inquiry before filing.
Most law firms using AI tools have no formal process for documenting attorney review. Here is what changes with LegalSeal:
| Capability | Without LegalSeal | With LegalSeal |
|---|---|---|
| Proof of attorney review | Verbal claim only | Cryptographic receipt with hash + bar number |
| Tamper detection | None | SHA-256 hash invalidates on any document change |
| Court-submittable evidence | No documentation | JSON receipt with timestamp and attestation |
| Bar number linked to review | No record | Attorney identity bound to document hash |
| Compliance with AI disclosure rules | Manual, inconsistent | Standardized protocol per document |
| Malpractice defense documentation | No evidence of due diligence | Timestamped proof of review process |
| Cost | $0 | $0 — open source (MIT license) |
LegalSeal provides cryptographic attorney attestation — a SHA-256 hash of the document combined with the attorney's bar number and timestamp creates a tamper-proof verification receipt proving the attorney reviewed the AI-generated output before filing. The receipt is downloadable as a JSON file and can be submitted to courts or retained in compliance records.
Documenting attorney review of AI output is critical for malpractice defense. LegalSeal creates a cryptographic seal linking the attorney's bar number to the specific document they reviewed, establishing a verifiable chain of accountability that demonstrates due diligence. This documentation shows that the attorney fulfilled their professional obligation to verify AI work product before relying on it.
LegalSeal generates a verification receipt containing the document's SHA-256 hash, attorney name, bar number, jurisdiction, attestation statement, and UTC timestamp. This receipt serves as cryptographic proof that a licensed attorney reviewed the document at a specific point in time. The document itself is never stored — only its hash — ensuring client confidentiality.
The LegalSeal Protocol is an open-source standard (MIT license) for attorney attestation of AI-generated legal documents. It uses SHA-256 cryptographic hashing to create tamper-proof verification receipts that prove human review occurred. The protocol specification is publicly available on GitHub and designed for integration with existing legal workflows and tools.
Over 716 lawyers have been sanctioned for unverified AI output, primarily for filing documents containing fabricated case citations generated by tools like ChatGPT. LegalSeal helps by requiring attorneys to formally attest they reviewed the document, creating a cryptographic record of that review that can be presented to courts as proof of due diligence under Rule 11 and state equivalents.