Rule 1414 A writing may be authenticated by evidence that: (a) The party against whom it is offered has at any time admitted its authenticity; or (b) The writin…

When you use a document in court, you need to show it is real. Two things can prove a document is authentic without needing other evidence.

First, if the other party ever said the document was real, that admission counts as proof. This could be something they said in writing, in a deposition, or even in casual conversation. Second, if the other party treated the document as real by acting on it, that behavior also proves it is authentic. For example, if someone made payments based on a contract, they cannot later claim the contract is fake.

These two ways of proving a document is real are based on the other party's own actions and words. Courts treat what people do and say as strong evidence, especially when it works against them later in a case.