What evidence helps prove that a contract was signed digitally?
To prove the legal validity of a digitally signed contract, having the signed document in your possession is not enough. It is essential to have technical and legal evidence that verifies the signatory’s identity, the integrity of the document and the legitimacy of the signature process.
Signatory’s identity
The system must unequivocally link the signature to a certain person by means of robust mechanisms such as a digital certificate, document verification, OTP or a combination of authentication factors. This evidence is key to proving who actually signed and avoiding identity spoofing, given that isolated elements like IP addresses do not automatically guarantee the signatory’s identity.
Document integrity
Assurance that the contents of the document have not been changed since it was signed by means of a hash and a qualified time stamp. This evidence can be used to show a judge that the signed document is exactly the same as the one submitted as proof.
Informed consent
Evidence that the signatory had access to the document, reviewed it and knowingly agreed to the contents, including timestamps, event logs, document versions, acceptance screens or signature flows. This point is important for providing proof of an express desire to sign.
Complete traceability
An auditable record of the complete signature process, including items sent, access, dates and times, IPs, devices, signature method and actions taken by each participant.Thanks to this traceability, it is possible to reconstruct the entire process and provide probative value in the event of a dispute.
Custody and storage
All evidence is available in verifiable formats for future use.Without proper custody, even a valid signature can end up lacking probative force over time.
Therefore, Logalty provides all this evidence in a comprehensive, automated manner, generating a final certificate of the electronic signature transaction that contains the signatory’s identity, document integrity, informed consent, complete traceability and custody of evidence. All of the above has probative value in court, enabling organisations not only to sign electronically but also to prove what was signed, who signed it, how and when it was signed, even years later, in an objective, verifiable and auditable manner.
Types of electronic signature and their probative force
Within the framework of Spanish and European regulations, especially in accordance with Regulation (EU) No 910/2014 (eIDAS) and Spanish Law 6/2020, on electronic trust services, there are three main categories of electronic signatures, each with distinct legal implications and probative force:
Simple electronic signature
This is the most basic form of electronic signature. It consists in any method in which the signatory can be identified, even if only in a limited manner and without advanced technical safeguards. Examples:
- Checking the “I agree” box on a website.
- Drawing your signature on a tablet or with a mouse, without collecting data such as speed, angle or pressure.
- Signing an online contract using an OTP code received by SMS.
This type of signature is valid but in the event of a conflict, additional proof will be required to show who actually signed and the signing conditions and safeguards, because the signature itself does not ensure robust identification or document integrity.
Advanced electronic signature
This is one step further in terms of security and reliability. The signatory can clearly be identified, the signature is linked to the signed document and it is possible to detect whether the document was modified after it was signed. Examples:
- Digitally signing a PDF with a qualified certificate in software, signature with two-factor authentication, combining personal credentials with an OTP code sent by SMS or app, associated with the signed document.
This type of signature offers strong probative force because it creates a record of the signatory’s identity and the signature process, which facilitates the defence before a judge in the event of a dispute.
Qualified electronic signature
This is the most robust type, meeting the strictest legal requirements according to the eIDAS Regulation. It is equivalent to a handwritten signature and is backed by a qualified certificate issued by a qualified trust service provider. Examples:
- Signing with an electronic ID card or a cloud-based qualified digital certificate.
- Using a secure device (such as a token or a cryptographic card)
This type of signature offers the greatest legal protection and the maximum probative force. It is the only option that is legally considered equivalent to a signature on paper throughout the European Union, with no need for additional evidence of its validity
How to prove validity in the event of a dispute
For an electronic signature to be upheld in court or in administrative proceedings, the mere existence of the signed document is insufficient.
You also need:
- Proof of identification: certificate, verification in advance, OTP, biometrics (where appropriate).
- Log of events and traceability: items sent and opened, IPs, devices and the sequence of actions.
- Time stamps and hashes: verifiable date/time and document fingerprint to prove integrity.
- Evidence report: document (e.g., PDF or XML) with full details of the signature transaction.
- Custody and storage: safe repository with access control and retention policies.
- IT expert report: independent analysis that confirms authenticity, integrity and chain of custody.
With this evidence, it is possible to reconstruct the signature act in an objective, verifiable and audited manner, thus ensuring that the contract is defensible in the event of a dispute.
Common mistakes that weaken the evidence
Although it is relatively simple to sign a document electronically, certain practices may compromise the probative force of a signature. It is important to understand these common mistakes to avoid legal risks and ensure that the electronic signature meets the required standards that make it defensible in court or in an audit. Basing the “identification” solely on the IP address or an email address.
- Lack of qualified time stamps or document fingerprint (hash).
- Not keeping the evidence report or storing it without safeguards.
- Being unable to reconstruct the exact contents signed (lack of versions).
- Mixing signed and unsigned documents without distinction in a folder.
Quick checklist before sending a document for signature
Before sending a contract to be signed electronically, it is advisable to check all the elements that will guarantee its validity and defensibility.
- Will I be able to identify the signatory with the robustness required in relation to risk involved (KYC/OTP/certificate)?
- Will there be a verifiable record of the exact contents signed (hash and versions)?
- Will I have a time stamp and complete log of events?
- Will I generate an exportable, auditable evidence report?
- Where and how long will I store the evidence?
- What is my plan if the signature is challenged (expert report, chain of custody, technical witnesses)?
FAQ
During the electronic signature process, questions often come up about validity, required type of signature and defence criteria. Knowing the responses to these questions helps you to make informed decisions, thus avoiding mistakes that could compromise the probative force of digitally signed contracts.
- Is a simple signature “invalid” by default?
No. It is valid, but its probative force is weaker and additional proof may be required to uphold it in court.
- Do I always need a qualified signature?
No. It depends on the risk and regulatory requirements in each case. A properly-instrumented advanced signature is sufficient in many contracts.
- What makes a signature defensible?
The combination of robust identification, document integrity, informed consent, traceability and custody.
Why choose Logalty?
Logalty enables you not only to sign digitally, but to do so with full legal defensibility and maximum certainty. Advanced qualified signature: Complies with eIDAS and Spanish Law 6/2020.
- Enhanced evidence: OTP, IP, time stamp, hash, evidence report.
- Qualified time stamp: Guarantees integrity and date.
- Safe custody: Evidence kept in storage for years.
- Legal recognition: Solution accepted in legal and administrative proceedings throughout Spain.
- Expert support: Advice and support in the event of a dispute.
Trust Logalty to ensure that your electronic signatures are truly defensible and secure.
Contact us if you would like your company to implement a secure electronic signature system, optimising your processes, complying with regulations in force and protecting your critical documents from unexpected events. Contact us for more information!
If you are self-employed or own an SME, sign your contracts safely with Logalnet, the digital platform of Logalty, and receive € 10 in free credit to test the electronic services and keep your business protected.
