Who bears the burden of proof when an electronic signature is contested?

By principle (Article 1353 of the Civil Code), whoever invokes the deed must prove its existence and validity. But if the signature is qualified, the presumption of reliability reverses the burden: it is up to the challenger to demonstrate that the process was deficient.

What is a presumption of reliability and how do you overturn it?

It is a legal mechanism that presumes a qualified signature to be reliable without its holder having to prove it. To overturn it, the adversary must provide contrary evidence: failure of identification, compromise of the device or alteration of the document.

What happens if the signatory denies having signed?

This repudiation is not enough to exclude the evidence. The holder opposes the audit trail, the certificate and the integrity hash. In case of serious contestation, the judge may order an expert examination to verify the authenticity of the process.

Does a simple signature allow you to win litigation?

Yes, but without automatic presumption: you must convince the judge of the reliability of the process through technical elements (identification, timestamping, integrity). The strength of the evidence file is decisive when the legal presumption does not apply.

Does the signature level influence the burden of proof?

Strongly. The qualified signature shifts the burden to the challenger; simple and advanced signatures leave the burden of establishing reliability to whoever invokes the deed. Choosing the right level means anticipating the allocation of proof.

Proof & Litigation

Burden of proof and challenge to an electronic signature

When a signatory contests having signed, everything hinges on the burden of proof: who must demonstrate what, and at what moment the burden shifts from one party to the other. The signature level determines whether you benefit from a favorable presumption or whether you must establish the reliability of the process. Here is how the allocation operates and how to secure your position upstream.

Updated on July 31, 2026

Legal framework

The burden of proof follows the principle of article 1353 of the Civil Code: whoever claims performance of an obligation must prove it, and whoever claims to be released from it must prove the fact that extinguished their obligation. Presumptions shift this burden. For a qualified signature, the presumption of reliability reverses the burden: it is up to the challenger to overturn it. For simple and advanced signatures, it falls to the person invoking it to establish the reliability of the process, with the judge assessing the evidence produced.

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Article 1353 of the Civil Code: whoever claims performance of an obligation must prove it; conversely, whoever claims to be released must justify payment or the fact that extinguished their obligation.
Article 1367 of the Civil Code: the reliability of the electronic signature process is presumed when it meets regulatory requirements; this presumption shifts the burden of proof to whoever contests it.
eIDAS Regulation (EU) No. 910/2014, article 25: the qualified signature benefits from the strongest presumption; its contestation requires the challenger to provide evidence to the contrary.
Articles 1368 and following of the Civil Code: in the absence of a legal presumption or when both parties have evidence, the judge decides by all means based on likelihood and reliability of the evidence produced.

Evidence elements to retain

Proof of the signatory's identification adapted to the signature level (identity verification, strong authentication, one-time code).

The timestamped audit trail tracing each step of the signing journey and the expressed consent.

The signature certificate and its validation chain, essential for invoking or defending a presumption of reliability.

The integrity fingerprint (hash) demonstrating the absence of document alteration after signing.

Associated contractual exchanges (e-mails, acceptance of terms) corroborating the intention to commit.

The service provider's documentation on the signature process, useful for establishing its reliability in the face of a challenge.

In case of dispute: the steps

1
Identify who bears the burden
Determine the starting point: whoever invokes the deed must in principle prove it (article 1353), unless a legal presumption reverses this burden in favor of the holder of a qualified signature.
2
Enable the presumption of reliability
If the signature is qualified, invoke the eIDAS presumption and Article 1367: the burden then shifts to the challenger, who must demonstrate a failure in the process.
3
Establish reliability for a simple or advanced signature
In the absence of a legal presumption, produce the audit trail, identification and integrity sealing to convince the judge of the reliability of the process and the reality of consent.
4
Respond to signature repudiation
Faced with a signatory who denies having signed, oppose the consistency of the technical file. If doubt persists, the judge may order electronic handwriting verification or expert examination.

Frequently asked questions

Who bears the burden of proof when an electronic signature is contested?: By principle (Article 1353 of the Civil Code), whoever invokes the deed must prove its existence and validity. But if the signature is qualified, the presumption of reliability reverses the burden: it is up to the challenger to demonstrate that the process was deficient.
What is a presumption of reliability and how do you overturn it?: It is a legal mechanism that presumes a qualified signature to be reliable without its holder having to prove it. To overturn it, the adversary must provide contrary evidence: failure of identification, compromise of the device or alteration of the document.
What happens if the signatory denies having signed?: This repudiation is not enough to exclude the evidence. The holder opposes the audit trail, the certificate and the integrity hash. In case of serious contestation, the judge may order an expert examination to verify the authenticity of the process.
Does a simple signature allow you to win litigation?: Yes, but without automatic presumption: you must convince the judge of the reliability of the process through technical elements (identification, timestamping, integrity). The strength of the evidence file is decisive when the legal presumption does not apply.
Does the signature level influence the burden of proof?: Strongly. The qualified signature shifts the burden to the challenger; simple and advanced signatures leave the burden of establishing reliability to whoever invokes the deed. Choosing the right level means anticipating the allocation of proof.

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