In Massachusetts, all evidence introduced at trial must first be authenticated. See Section 901 of Article IX of the Massachusetts Guide to Evidence.
In the words of the Supreme Judicial Court:
In order to be material, a thing offered in evidence genuinely must be what its proponent represents it to be.
Commonwealth v. Lacorte, 373 Mass. 700, 704.
So how does a litigant prove, by a preponderance of the evidence, that an item he seeks to introduce at trial is in fact true and genuine? According to the SJC:
Its authenticity must be stipulated or else proved like any other fact. Such proof of authenticity usually takes the form of testimony of a qualified witness either (1) that the thing is what its proponent represents it to be, or (2) that circumstances exist which imply that the thing is what its proponent represents it to be.
Id.
Whether the authentication requirement has been satisfied is a question for the trial judge. As stated by the Appeals Court:
When assessing the authenticity of evidence, the judge, acting as gatekeeper, must determine whether there is evidence sufficient, if believed, to convince the jury by a preponderance of the evidence that the item in question is what the proponent claims it to be. The item may be authenticated by direct or circumstantial evidence, including its [a]ppearance, contents, substance, internal patterns, or other distinctive characteristics.”
Commonwealth v. Gonsalves, 99 Mass.App.Ct. 638, 641-642 (2021).
Certain types of evidence (court records, acknowledged documents, etc.) are “self-authenticating” and require no testimony or foundational evidence before they may be used at trial. For a list of such documents see Mass.G.Evid. § 902.