What is the claim of guilt or innocence made by the defendant in a criminal action known as?

The claim of guilt or innocence made by the defendant in a criminal action is known as a plea. This is a formal response by the defendant to the charges brought against them in court. When a defendant enters a plea, they may choose to plead guilty, not guilty, or no contest (nolo contendere), each of which carries different legal implications and consequences. The plea serves as a crucial part of the criminal justice process, as it sets the stage for how the case will proceed, whether it goes to trial or results in a plea agreement.

In legal terms, a statement could refer to any verbal or written communication made by a person, without the specific context of a legal proceeding. Assertion and declaration also lack the specific legal connotation associated with a defendant's response to criminal charges. Hence, "plea" is the appropriate term in this context.