A person who signs an affidavit and swears to its truth is called an affiant. An affiant must have the intellectual capacity to take an oath or make an affirmation. An affiant must have personal knowledge of the facts described in the affidavit. There is no age requirement for an affiant. An affidavit is valid as long as the affiant is old enough to understand the facts and significance of the oath or affirmation he or she makes. A criminal conviction does not make a person incapable of making an affidavit. However, a person who has been adjudicated as mentally incompetent is incapable of making an affidavit.
A person familiar with the matters in question may make an affidavit on behalf of another; however that person’s authority to make the affidavit must be clear. For example, a guardian may make an affidavit for a minor or insane person incapable of doing so. An attorney can also make an affidavit for a client if it is impossible for the client to do so. Similarly a personal representative, agent, or corporate officer or partner may execute an affidavit that indicates the capacity in which the affiant acts. An affiant is strictly responsible for the truth and accuracy of the contents of the affidavit. If false statements are made, the affiant can be prosecuted for perjury.