Evidentiary Value of Blockchain Notarization

What is evidentiary value?

In French and European legal systems, evidentiary value refers to the weight that a court assigns to a piece of evidence when deciding a case. The French legal tradition uses two closely related terms: force probante (the probative force or weight of evidence) and valeur probatoire (the evidentiary or probative value). While often used interchangeably, force probante emphasizes the strength with which a piece of evidence can convince a judge, whereas valeur probatoire refers more broadly to its admissibility and legal standing within a proceeding.

For digital evidence, evidentiary value depends on three core properties: integrity (the data has not been altered), authenticity (the source of the data is identifiable), and reliable dating (the time at which the data existed can be verified). A technology that can guarantee all three provides evidence with strong probative force. This is precisely where blockchain notarization enters the picture.

French legal framework

France has progressively built a modern legal framework that recognizes electronic evidence and, more recently, blockchain-based proofs. Understanding these key texts is essential for anyone seeking to leverage blockchain notarization in a legal context.

Article 1358 of the Civil Code: Freedom of proof

Article 1358 of the French Civil Code (Code civil) establishes the principle of freedom of proof (liberte de la preuve) for legal facts (faits juridiques). This means that, outside of specific situations where the law requires a particular form of proof (such as written contracts above a certain value), any means of evidence may be presented to a court. This includes electronic records, digital files, screenshots, and, crucially, blockchain-anchored proofs.

This principle is foundational because it opens the door for innovative technologies. Blockchain notarization does not need a specific statute authorizing it as proof: under Article 1358, it is already admissible as a mode de preuve (means of proof). The question then becomes one of evidentiary weight, how much a judge will trust the evidence.

Article 1366 of the Civil Code: Electronic documents

Article 1366 takes the framework further by explicitly granting electronic documents (ecrits electroniques) the same evidentiary value as paper documents, provided that two conditions are met: the identity of the author can be properly established, and the document was created and stored in conditions that guarantee its integrity.

This article is particularly significant for blockchain notarization. A cryptographic hash anchored on a public blockchain satisfies the integrity requirement in a remarkably robust way: the hash is computed deterministically, stored on an immutable ledger, and can be independently verified by anyone at any time. When combined with proper identification mechanisms (API keys, authenticated accounts, or eIDAS electronic signatures), the authenticity condition is also addressed.

Decree of 24 December 2018: Blockchain recognized as a valid proof device

The Decree of 24 December 2018 marks a landmark in French law. This decree formally introduces the concept of Dispositifs d'Enregistrement Electroniques Partages (DEEP), Shared Electronic Recording Devices, which is the official French legal term for blockchain and distributed ledger technologies.

While the decree was initially enacted in the context of financial securities (specifically for the issuance and transfer of unlisted securities via blockchain, implementing the Ordonnance n 2017-1674 of 8 December 2017), its significance extends far beyond finance. By acknowledging that a DEEP can serve as a valid recording mechanism with legal effects, French law implicitly recognizes that data recorded on a blockchain carries evidentiary weight. Legal scholars and practitioners have since extended this reasoning to digital evidence in general: if the French state trusts blockchain enough to record financial transactions, its properties of immutability and transparency apply equally to evidentiary records.

AFNOR NF Z67-147 standard

The AFNOR NF Z67-147 standard defines operational procedures for internet-based reports (constats par internet). Originally designed for bailiffs (commissaires de justice) performing online findings, this standard provides a rigorous methodology for capturing digital evidence in a way that courts will consider reliable.

The standard covers aspects such as the technical environment used for the capture (browser configuration, DNS resolution, cache clearing), the metadata recorded alongside the evidence, and the procedures for ensuring reproducibility. When blockchain notarization is performed in compliance with or in reference to this standard, the resulting evidence benefits from an additional layer of credibility. A hash anchored on a blockchain following NF Z67-147 procedures carries more weight than one without such procedural guarantees.

Hierarchy of evidence

Not all digital evidence is created equal. In practice, French courts assess digital proof along a spectrum of evidentiary strength. Understanding this hierarchy helps organizations choose the right level of protection for their needs.

At the base level, simple proof includes standard digital records: a screenshot, a saved email, a log file. These are admissible under the freedom of proof principle, but they are easily contestable. An opposing party can argue that the file was modified, the timestamp was fabricated, or the screenshot was doctored. The burden of demonstrating reliability falls entirely on the presenting party.

The next level, qualified proof, involves technologies that add verifiable guarantees. A hash anchored on a public blockchain falls into this category. The hash provides mathematical proof of integrity (any modification to the original data would produce a different hash), and the blockchain provides a tamper-proof timestamp. This is considerably harder to contest: an opposing party would need to demonstrate that the entire public blockchain was compromised, which is practically infeasible for established networks.

At the highest level, blockchain + eIDAS proof combines blockchain anchoring with an eIDAS-qualified timestamp issued by an accredited Trust Service Provider (TSP). Under EU Regulation No 910/2014, a qualified electronic timestamp benefits from a legal presumption of accuracy, the burden of proof shifts to the party contesting the evidence. This is the strongest form of digital evidence currently available in the European legal framework.

How blockchain provides evidentiary value

Blockchain notarization builds evidentiary value through a chain of cryptographic guarantees, each reinforcing the others.

Integrity through cryptographic hashing. The process begins with a cryptographic hash function (such as SHA-256, SHA-384, or SHA-512). The hash is a fixed-length digital fingerprint of the original data. It is deterministic (the same data always produces the same hash), one-way (the original data cannot be reconstructed from the hash), and collision-resistant (it is computationally infeasible to find two different inputs producing the same hash). If even a single bit of the original data changes, the resulting hash is entirely different. This provides a mathematically verifiable proof that the data has not been altered since the hash was computed.

Objectively verifiable date via public blockchain. When the hash is recorded on a public blockchain, it receives a timestamp that is inherently trustworthy. Unlike a timestamp from a private server (which the data owner controls and could manipulate), a blockchain timestamp is embedded in a block validated by a decentralized network of independent nodes. The block's position in the chain, confirmed by subsequent blocks, provides an objective, publicly auditable proof that the hash existed at or before a specific point in time.

Chain of trust: hash, Merkle tree, blockchain transaction. In practice, most notarization services (including Anchorify) use a Merkle tree to batch multiple hashes into a single blockchain transaction. Individual hashes form the leaves of the tree, which are recursively combined to produce a single root hash (the Merkle root). This root is then anchored on the blockchain. To verify any individual hash, one only needs the hash itself, the corresponding Merkle proof (a small set of intermediate hashes), and the on-chain transaction. This creates an efficient, scalable, and independently verifiable chain of trust from the original data to the blockchain.

The role of the bailiff

In the French legal system, the bailiff, known historically as huissier de justice and now officially as commissaire de justice since the 2022 reform merging the professions, plays a unique and powerful role in establishing evidence. A bailiff is a ministerial officer (officier ministeriel) authorized by the state to produce authentic acts (actes authentiques), which carry the highest evidentiary weight in French law.

Certifying blockchain content. A bailiff can examine blockchain records and issue an official finding (constat) attesting to their content at a given moment. This involves verifying the blockchain transaction, confirming the hash correspondence, and documenting the verification process. The resulting constat is an authentic act that a court will accept without requiring further proof of its accuracy.

Creating an authentic legal snapshot. The bailiff's constat effectively creates a legally recognized snapshot of the blockchain evidence. It bridges the gap between the technical world (where the proof exists on-chain) and the legal world (where a court needs a document it can evaluate). The bailiff attests: "At this date and time, I verified that transaction X on blockchain Y contains hash Z, and that hash Z corresponds to the document presented to me."

AFNOR NF Z67-147 compliance. When performing internet-based findings, bailiffs may follow the AFNOR NF Z67-147 standard. This standard ensures that the technical environment is properly configured (cleared cache, direct DNS resolution, no proxy interference) and that the capture process is documented in a reproducible manner. A constat produced under this standard is particularly robust against technical challenges in court.

Combined strength: blockchain + bailiff. The combination of blockchain notarization and a bailiff's constat is especially powerful. The blockchain provides continuous, tamper-proof, publicly verifiable evidence. The bailiff provides the legal formalism that French courts require. Together, they create evidence that is both technically unassailable and legally impeccable. This combination is increasingly recommended by legal practitioners for high-stakes intellectual property, contractual, and compliance matters.

Practical implications for businesses

Understanding evidentiary value is not merely an academic exercise, it has concrete consequences for businesses operating in France and Europe.

Intellectual property protection. Creators, designers, and software developers can establish priority of creation by hashing their work and anchoring the hash on a blockchain. In a dispute, this provides a verifiable proof of existence predating the alleged infringement. The 2025 Marseille court ruling confirmed this approach, recognizing blockchain timestamps as valid evidence of copyright ownership.

Contractual and regulatory compliance. Businesses subject to audit obligations, financial services, healthcare, pharmaceuticals, food safety, can notarize critical records to demonstrate that data existed in a specific state at a specific time. This is valuable for proving compliance with record-keeping requirements and for defending against allegations of data manipulation.

Pre-litigation evidence preservation. When a dispute is foreseeable, businesses can proactively notarize relevant data to prevent accusations of evidence tampering. Because blockchain timestamps are objective and independently verifiable, they are far more credible than internal server logs or self-certified timestamps.

Cross-border evidence. For businesses operating across EU member states, combining blockchain notarization with eIDAS-qualified timestamps ensures that evidence is recognized under a harmonized European framework. The eIDAS regulation provides mutual recognition across all 27 member states, eliminating jurisdictional uncertainty.

How Anchorify strengthens evidentiary value

Anchorify is specifically designed to maximize the evidentiary value of digital proofs through a combination of architectural choices and legal-grade features.

Hash-only by design. Anchorify never receives or stores your original files. You compute a cryptographic hash locally and submit only the hash to the API. This design eliminates privacy concerns and data transfer risks, while ensuring that the integrity proof is mathematically bound to your exact data. In a legal proceeding, you retain full control of the original evidence while the hash on the blockchain serves as an independent, verifiable witness.

Multi-blockchain anchoring. Rather than relying on a single blockchain, Anchorify anchors proofs on multiple public blockchains (available on Pro and Enterprise plans). This provides redundancy and long-term resilience: even if one network's relevance diminishes over decades, your proof remains verifiable on other chains. It also strengthens evidentiary value by demonstrating that the proof is not dependent on any single technology provider.

eIDAS-qualified timestamps. For the highest level of legal assurance, Anchorify's Enterprise plan integrates eIDAS-qualified timestamps from accredited Trust Service Providers. These timestamps benefit from the legal presumption of accuracy under EU Regulation No 910/2014, meaning a court must accept the timestamp as accurate unless the opposing party can prove otherwise. This effectively reverses the burden of proof.

Merkle tree transparency. Every notarization includes a complete Merkle proof, allowing independent verification of the hash's inclusion in the on-chain transaction. This transparency is critical for evidentiary purposes: it means that verification does not depend on Anchorify's continued existence or cooperation. The proof is self-contained and can be verified by any technically competent party using only public blockchain data.

Signed Proof Documents. Anchorify generates exportable proof documents (available on Pro and Enterprise plans) that bundle all the cryptographic evidence needed for verification: the original hash, the Merkle proof, the blockchain transaction reference, and the optional eIDAS timestamp token. These documents are designed to be presented directly to courts, auditors, or legal counsel, serving as a complete, self-standing evidence package.

By combining these capabilities, Anchorify enables businesses and legal professionals to produce digital evidence that sits at the top of the evidentiary hierarchy: blockchain-anchored, optionally eIDAS-qualified, independently verifiable, and ready for judicial scrutiny.