For legal and official purposes, evidentiary documents and other official documents are usually required to be in the official language(s) of jurisdiction. In certain countries, the translator is required to swear an oath to certify that the document translated is the legal equivalent of the source text. In many cases, only a specific category of translators is permitted to swear such oaths. Occasionally translations are only accepted as the legal equivalent if accompanied by the original document or a sworn/certified copy.  Even if a translator is specialised in legal translations or is a lawyer in their country, it does not necessarily make them a sworn translator. The procedure for translating documents into their legal equivalents is specific to the country in question.
You can find more information relating to this under the heading of ‘Certified translation’.