Legal validity
Signing electronically is not the same as having a signature that holds up in court. What decides that is the signature’s level and the evidence that comes with it. This page explains what AssinaJá produces, and under what law.
The legal basis
Section titled “The legal basis”Two instruments underpin everything else:
- Regulation (EU) No 910/2014 — eIDAS, which defines the three levels of electronic signature and requires their recognition across the Union.
- Decreto-Lei n.º 290-D/99, de 2 de agosto, as amended by Decreto-Lei n.º 88/2009, de 9 de abril — the Portuguese regime for electronic documents and digital signatures.
From eIDAS comes the principle that settles the most common doubt: an electronic signature cannot be denied legal effect merely for being electronic.
The three levels, and what each is worth
Section titled “The three levels, and what each is worth”| Level | eIDAS | What it is |
|---|---|---|
| SES | Art. 3.10 | Simple electronic signature |
| AES | Art. 3.11 and 26 | Advanced: uniquely linked to the signer, under their sole control, detects alteration |
| QES | Art. 3.12 and 25.2 | Qualified: an advanced signature, created by a qualified device with a qualified certificate |
Note the QES definition: it is an AES plus two conditions. The levels contain one another rather than sitting side by side — which is why texts describing Chave Móvel Digital as “advanced” are not wrong.
Evidential weight in Portugal
Section titled “Evidential weight in Portugal”This is the practical part. Under the Portuguese Código Civil, a signed electronic document is worth different things depending on the signature level:
| Signature | Treated as | Consequence |
|---|---|---|
| Qualified (Chave Móvel Digital) | A private document with recognised authorship, under article 376.º of the Código Civil | Authorship is presumed; whoever denies it must prove otherwise |
| Simple, without a certificate | Other private documents | Subject to the court’s free assessment |
The difference is who carries the burden of proof. With a simple signature, it falls to you to convince the court the signature is genuine. With Chave Móvel Digital, it falls to the other party to show it is not.
If the electronic document does not take written form, a qualified signature makes it equivalent to a mechanical reproduction.
What Portuguese law does not allow to be signed this way
Section titled “What Portuguese law does not allow to be signed this way”Some acts require additional formalities — a public deed, an authenticated private document, or notarised signatures. A simple electronic signature does not cover them. Among others:
- Transfer of real estate and creation of mortgages
- Incorporation of companies
- Enforcement instruments (títulos executivos)
- Powers of attorney for those acts
- Loan agreements above €25,000
Before using AssinaJá for a formal act, confirm the law does not require more than a signature.
Independent proof
Section titled “Independent proof”Validity does not rest on AssinaJá’s word. Documents are validated by third-party tools:
- Adobe Reader DC, in the signature panel
- The European Commission’s DSS Demo Validator, against the official EU Trust List
In a reference validation, DSS v6.4 classified a document signed with Chave
Móvel Digital as QESig / TOTAL_PASSED — qualified signature, validation
fully passed.
See Validate a signed document.
The limits, stated plainly
Section titled “The limits, stated plainly”A page about legal validity that only said what goes well would not be useful. These limits are the ones AssinaJá’s own signature policy declares:
AssinaJá is not a qualified trust service provider. The qualified character of the signatures comes exclusively from AMA. The platform prepares, collects and assembles — it does not issue qualified certificates.
The platform seal is AES, not QES. Every document carries a certifying seal issued by an AATL authority, which guarantees integrity — but that authority is not on the EU Trust List, and the seal does not turn a simple signature into a qualified one.
ID Confirmation is self-declared. The signer types their identity document number; there is no chip reading, no biometrics, no check against official records. It strengthens the evidence; it does not make the signature qualified.
SMS OTP does not reach advanced. It proves control of a phone number, which is substantial, but there is no per-signer certificate and no sole control of a key.
Only Chave Móvel Digital is qualified. If what you need is equivalence to a handwritten signature, it is the only route — see Qualified signatures with CMD.