Is an electronic signature legally binding?

This is the first question anybody asks before sending a contract by email, and the honest answer is that the law settled it a long time ago. What has not been settled — what is never settled in advance — is whether you can prove what happened. That distinction is the whole subject.

The law is not the hard part

In the United States, the ESIGN Act of 2000 and the UETA, adopted in nearly every state, say a signature cannot be denied legal effect solely because it is electronic. In the EU, eIDAS says the same thing and goes further, setting out three tiers of electronic signature. The United Kingdom, Canada, Australia, and most of the world's trading economies have equivalents.

None of these laws require a particular technology. They do not say you need a certificate, a smart card, or a particular vendor. They say an electronic signature is a signature, and then they leave the interesting question — was it really them, and did they really agree — to ordinary rules of evidence.

The three eIDAS tiers, briefly

• Simple (SES) — any electronic mark made with intent to sign. A typed name, a drawn squiggle, clicking a button. Admissible; its weight depends on what else you can show.
• Advanced (AES) — uniquely linked to the signer, capable of identifying them, created with something under their sole control, and tamper-evident afterwards.
• Qualified (QES) — an advanced signature made with a certified device and a certificate from a qualified trust service provider. In the EU this is the legal equal of a handwritten signature, and it is the only tier that reverses the burden of proof.

Almost every commercial contract signed electronically today is a simple or advanced signature, including the ones sent through the big providers. Qualified signatures require the signer to have a government-issued identity credential, which is why they show up in regulated finance and property work and almost nowhere else.

What actually decides a dispute

If a signature is ever challenged, nobody argues about whether electronic signatures are valid in general. They argue about this one. The questions are always the same:

• Who was sent the document, at what address, and when?
• Did that person open it, and from where?
• What exactly did they see at the moment they signed — the same bytes you are now holding, or something else?
• Has the document changed since?

This is why an audit trail is not a nice-to-have feature listed after the templates. It is the product. Timestamps, the IP address and user-agent captured at signature, a hash of the exact bytes presented, and a cryptographic signature over the finished file are what turn a click into evidence. Without them you have an email that says somebody agreed.

Where electronic signatures do not work

There are real exceptions, and they are narrower than people assume but they are not empty:

• Wills and testamentary instruments, in most jurisdictions.
• Some family-law documents — divorce, adoption.
• Certain property transfers and deeds, depending on the country and sometimes the region.
• Anything a regulator specifically requires to be notarised or executed on paper.

This is background, not legal advice. Whether an electronic signature is sufficient for a particular document in a particular country is a question for someone who can be held responsible for the answer.

A practical rule

For ordinary commercial work — NDAs, consulting agreements, freelance contracts, licences, statements of work — an electronic signature with a real audit trail is not a compromise. It is better documented than the paper version, which typically has no record of when it was read, by whom, or whether the copy in your drawer matches the copy in theirs.