Use Case
Blockchain Timestamps for Attorneys and Litigation Counsel
Tamper-evident digital evidence with adversarial verifiability. How trial counsel, eDiscovery teams, and litigation support use SHA-256 blockchain anchoring for evidence that holds up under cross-examination.
The evidentiary problem
Digital evidence presents an authentication challenge that physical evidence doesn't. A photograph can be altered. A document's metadata can be changed. A file's creation date can be edited. In a litigation context, the question isn't just what the file shows — it's whether the file presented in court is the same file that was originally captured, and whether it existed at the time the proponent claims.
Traditional authentication relies on witness testimony, custodian declarations, and chain-of-custody documentation. These mechanisms work, but they invite cross-examination on every link in the chain. A blockchain-anchored hash addresses the integrity element with cryptographic certainty: the file either matches the on-chain record bit-for-bit, or it doesn't. Tampering is mathematically detectable.
How ProofLedger fits the federal evidentiary framework
FRE 901(b)(9): Authentication by process
Rule 901(b)(9) allows authentication by "evidence describing a process or system used to produce a result and showing that the process or system produces an accurate result." The process here is well-defined: SHA-256 hashing of the file bytes (NIST FIPS 180-4), on-chain transaction recording the hash, blockchain network consensus establishing the block timestamp. Each step is deterministic, testable, and independently verifiable.
FRE 902(13) and 902(14): Self-authenticating electronic records
Records generated by an electronic process or system (902(13)) and data copied from an electronic device (902(14)) are self-authenticating with a qualified certification. A custodial declaration that ties the file, hash, and on-chain record together can satisfy these provisions, eliminating the need for live custodial testimony at trial.
Daubert reliability factors
The Daubert standard's four factors — testability, peer review, known error rate, general acceptance — are all satisfied by SHA-256 anchoring. SHA-256 is NIST-standardized with decades of cryptographic peer review (FIPS 180-4). Collision probability is mathematically bounded at 2−128. Blockchain consensus mechanisms are openly documented in the computer science literature. An expert witness can establish each factor with primary source citations.
Practical applications in litigation
- Pre-litigation hold preservation — anchor relevant files at the moment a litigation hold is issued. The on-chain timestamp documents what specifically was preserved and when, independent of the firm's internal record-keeping.
- eDiscovery production validation — anchor production sets at the moment of delivery. If opposing counsel later disputes the contents of a production, the anchor proves the exact files produced and on what date.
- Spoliation defense — counsel facing a spoliation motion can demonstrate that the produced files match the anchored versions, establishing that no post-collection modification occurred.
- Expert witness exhibit preservation — anchor expert reports, exhibit files, and demonstrative materials. The chain of timestamps documents the expert's work product and supports authentication at trial.
- Settlement and licensing documents — anchor signed agreements and supporting exhibits. Tamper-evident proof of the executed version supports enforcement against later claims of modification.
- IP enforcement evidence — anchor screenshots, scraped pages, and downloaded files used as evidence of infringement. The anchor binds the captured state to a specific timestamp, addressing common challenges to web-evidence authenticity.
The adversarial verification standard
A common cross-examination challenge to third-party timestamp services is dependency on the service provider: "How do we know ProofLedger didn't backdate this record?" ProofLedger addresses this by design. The verification process does not require ProofLedger's cooperation, servers, or continued existence.
Opposing counsel runs pip install verify-proof on their own machine, executes the CLI against the file in question and the proof ID, and the tool queries the public Polygon or Bitcoin blockchain directly. The blockchain itself is the source of truth. ProofLedger is the convenience layer; the proof exists independently of the convenience layer.
File content stays privileged
ProofLedger never receives the file content. The SHA-256 hash is computed in the local browser before any network transmission. The 64-character hex hash is mathematically impossible to reverse-engineer into the original file. Privileged communications, attorney work product, confidential client materials, and sealed evidence can all be anchored without disclosure risk.
API integration for litigation support platforms
For eDiscovery vendors, document management systems, and litigation support platforms, the REST API supports programmatic anchoring at scale. The Formal Legal / Compliance tier ($99.99/month) includes unlimited Polygon proofs and full API access. Typical integration: anchor every uploaded document at the moment of ingestion into the case management system.
Pricing
Baseline Access (free, 5 lifetime Polygon proofs) for evaluation. Standard Evidence Access ($9.99/month, 100 proofs) for solo practitioners. Elevated Evidence Access ($49.99/month, high-volume) for active litigation. Formal Legal / Compliance ($99.99/month, unlimited + API) for litigation support and eDiscovery integration. Full pricing →