You probably have a feel of what it is: notarisation (or for American-English writers: notarization), legalisation (or: legalization) and apostilles. But there are nuances between their meanings and you might not fully know what it is. This blog explains the terms.
The signature block often starts by saying that the contracting party is duly represented by its signatory. There is no need to explicitly state this; if the signatory is not authorised (whether in accordance with the statutory rules or under case law) the represented party would not be bound by the contract and the signatory would be personally liable vis-à-vis the other party.
When the other party insists that a signatory’s due authorisation is formally confirmed, then in most cases a copy of the signatory’s passport (or other appropriate ID) would be acceptable. If a party requires a higher level of certainty, also an extract from the commercial register or court registry would be required. The highest level of certainty is typically sought by a notary (who needs to execute a notarial deed) or by a public official since they must exclude the chance of fraud. Instead of a ‘copy passport’ the ‘legalisation’ of the other party’s authorisation would need to be established. Such legalisation requires an apostille.
Apostille. In short, an apostille is the French word for a certification commonly used to refer to the legalisation of a document for use in another jurisdiction. The apostille or legalisation ascertains that the signature of the legalised document is authentic. Such ‘legalised documents’ must be accepted in the countries that have signed the Hague Convention. Where the apostille-issuing country is not a party to the Hague Convention, usually an additional diplomatic or consular confirmation of authenticity is necessary.
Legalisation and notarisation. In practice, an apostille is not much more than an extra page (attached to the legalised document) with a stamped legalisation statement (as required by the Hague Convention) and, in some jurisdictions, one or more colourful stamps (for the taxes and levies paid), signed by an official. The official is normally a consul, a court or other public official who ‘legalises’, by means of the apostille, the authenticity of the signatory of another official, typically a civil notary. The latter has actually investigated and ascertained what needs to be established in the relevant context the formalities up to the notary’s signature, are sometimes called ‘notarisation’.
What to legalise? In relation to the execution of an agreement, the legalised document should establish: (i) the names of the persons who are duly entitled to represent the relevant contracting party; and (ii) whether that representative (and not another person) has indeed signed the legalised document.
Example. For example: in many continental European jurisdictions, the transfer of shares requires a notarial deed of transfer; because of this formality, a transfer is often done on the basis of a power of attorney. In order for the power of attorney to be a valid proof of authority, the notary will ascertain that the seller is validly transferring the shares (and the same applies to the acquisition by the purchaser). Therefore, the notary needs to establish both: (i) who is duly entitled to represent the seller; and (ii) whether that representative (and not another person) has indeed signed the relevant power of attorney. Accordingly, the notary needs to have a statement under the law governing the internal affairs of the selling entities (i.e. that according to the articles of association, the seller can be represented in a certain manner), as well as a statement that the person who signed the power of attorney is indeed the representative (i.e. the signatory needs to go to a notary who will establish his or her identity on the basis of a valid ID and witness signature of the power of attorney). Although the legalisation of a party’s legal acts would typically be certified by one and the same certification of a notary (and subsequently the court), it may well be that two apostilled documents are delivered depending on where the representative actually is i.e. one ascertaining how the party can be represented and one stating that the signature is actually that of such duly authorised representative.
 The Hague Convention Abolishing the Requirement of Legalisation for Foreign Public Documents (1960).