Legal Definitions - judicial oath

A judicial oath is a solemn declaration made by a person in a legal proceeding, usually in open court, in which they swear to tell the truth. The person making the oath invites punishment if they are found to be lying or breaking a promise. The legal effect of an oath is to subject the person to penalties for perjury if the testimony is false.

For example, a witness in a court case takes an assertory oath to attest to some factual matter. A judge takes an oath of office before entering into the duties of their public office. A soldier or sailor takes an oath of allegiance to maintain fidelity to their government.

These examples illustrate how a judicial oath is a formal declaration made under the sanction of an appeal to God or a revered person or thing, and how it is used to ensure that the person making the oath is telling the truth or will be bound to a promise.