Evidence Act 1929

the age of a person is relevant to proceedings before a court; and

a document that appears to be a certified copy of, or extract from, a register of births kept under an Australian law, or under the law of the country in which the person was born, is produced to the court;

the name of the person to whom the document relates is the name or a former name of the person whose age is to be established, it will be presumed, in the absence of evidence to the contrary, that the person whose age is to be established is the person named in the document produced to the court and that the date of his or her birth is the date of birth shown in that document.