(1) A person commits the offense of perjury if in any official proceeding the person makes, under an oath required or authorized by law, a false statement which the person does not believe to be true.
(2) No person shall be convicted under this section unless the court rules that the false statement is a "materially false statement" as defined by section [710-1000]. It is not a defense that the declarant mistakenly believed the false statement to be immaterial.
(3) Perjury is a class C felony.