An English-speaking lawyer working with Dutch legal professionals soon notices that certain English words tend to be overused and used in ways that do not seem conventional.

One of those words is “legalise” or “legalisation”.  (Some would spell this as “legalize” and “legalization”, especially in the US.)

Legalise = to make lawful

In everyday English, “legalise” means to make something that was previously illegal permissible by law. Example: “Euthanasia has been legalised in the Netherlands. This illustrates the primary usage of “legalise” as understood by all English speakers.

Legalise = specific international process in the Hague Apostille Convention

“Legalise” is not ordinarily a legal term in English. Its usage in the sense of “make legal” (as explained above) is not particularly legal in nature. “Legalise” is not found in Black’s, Oxford DOL or Garner in this sense.

However, in the context of the authentication of documents under the Hague Apostille Convention, “legalise” is specifically used in the sense of “authenticate” or “certify the authenticity of”. Art. 2 of this convention states:

For the purposes of the present Convention, legalisation means only the formality by which the diplomatic or consular agents of the country in which the document has to be produced certify the authenticity of the signature, the capacity in which the person signing the document has acted and, where appropriate, the identity of the seal or stamp which it bears.

 This usage is reflected in this definition given on the website of the UK Notaries Society:

Legalisation is the process by which the signature and seal of the notary are authenticated by the Foreign Office and the Foreign Embassy.

In the context of the Hague Apostille Convention, British notaries use the term “legalise” in the same sense as Dutch notarissen.  

The following description from Kentucky gives an American view:

Some documents intended for use abroad (such as birth certificates, death certificates, marriage certificates, grade transcripts and diplomas, adoption papers, and corporate documents) require some form of authentication. The Secretary of State provides this authentication in the form of either an apostille or a certificate of authentication. Authentications are often called legalizations or incumbencies. An apostille is a form of authentication used for countries which are parties to the Hague Convention, which abolished the need for legalization of foreign public documents.

The problem: “legalise” is not clear and correct

Dutch legal professionals seem to use only the word “legalise” in referring to the authentication process. They seldom use “authenticate”.

When a Dutch notaris asks a client to “legalise a document”, it’s not always in the context of the Hague Apostille Convention (i.e. embassy or Foreign Office approval). Indeed, it seems usually not to be used in that strict sense.

The English word “legalise” is (when used in this sense) a specific legal term of art that refers specifically to a process in Hague Apostille Convention. If “legalise” is used at all in English, it should be reserved for this context.

Further, when “legalise” is used unclearly like this by a Dutch civil-law notary, it’s quite possible that the client may not know what is being asked. Most English speakers do not use the word “legalise” in the sense of “authenticate”. Oxford does not list this as a meaning for “legalise”.

Fortunately, most Dutch notarissen prudently explain the requirements in more detail, so the use of the word “legalise” in this way does not necessarily lead to problems.

So why was the word English “legalise” used in the English version of the Hague Apostille Convention? I haven’t researched this, but I’m afraid that the result might be that it is another example of the unconventional English that emanates from the EU and other international bodies. Perhaps it’s an overly literal translation of a French word.

“Authenticate” and “authentication”

The phrase used on the website for UK notaries is “authenticate the documents”. In the Kentucky description above, notice the prominent role played by the word “authentication”.

“Authenticate” and “authentication” are the right words. Dutch legal professionals tend to use the word “legalise” in situations in which English speakers use “authenticate”.

Authenticate means “to prove or show to be true, genuine or valid”. Here are some examples of the phrases used in English:

  • to authenticate a document / the authentication of a document
  • to authenticate a signature / the authentication of a signature
  • to authenticate the identity of the person signing / the authentication of someone’s identity
  • to authenticate a transaction / the authentication of a transaction
  • to authenticate a company’s existence / the authentication of a company’s existence


A “certify” phrase is also often used in this context by English speakers.  However, “certify” shouldn’t be used on its own. The phrase “certify a document” (although occasionally used) is not clear. To be clear, “certify” should be combined in a phrase with the word “authenticity” or “genuine”. Here are a few examples:

  • to certify the authenticity of a document / to certify that a document is genuine
  • to certify the authenticity of a signature / to certify that the signature is genuine
  • to certify that the person who signed the document was genuinely X
  • to certify that a transaction genuinely occurred
  • to certify the valid corporate existence of X 

“Notarise” and “notarisation”

Garner says the word “notarise” is “in some quarters [of the UK], considered something of an atrocity” (DMLU), but googling indicates that “notarise” and “notarisation” are actively used by British notaries.

However, “notarise” is a somewhat meaningless, broad verb. It can be used to refer to any notarial process. It does not clearly indicate “authenticate”.

Other words and phrases

Other words and phrase are also used in English in the sense of legaliseren: “to verify”, “to validate”, “to notarially validate”, “to attest to the authenticity of”, and so on.


  1. When referring to the authentication of documents, signatures, identities, transactions and corporate existence, reserve the words “legalise” and “legalisation” for situations involving the Hague Apostille Convention process. Explain the process using the word “authenticate”. It may be worth explaining in more detail what you are asking for exactly. 
  2. In other situations, it is better to use “authenticate” and “authentication”.
  3. The term to use may depend somewhat on the process that applies in the jurisdiction and on the situation.

Greg Korbee (Originally published in January 2014. Republished in February 2019.)

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