Rule 1400 Authentication of a writing means (a) the introduction of evidence sufficient to sustain a finding that it is the writing that the proponent of the ev…

When you want to use a document as evidence in court, you first have to show that the document is what you say it is. This is called authentication.

For example, if you claim a letter was written by a specific person, you need to provide enough proof to back that up. That proof could be a witness who saw the person write it, handwriting comparison, or other facts that support your claim.