Texas Penal Code

37.02. Perjury

(a) A person commits an offence if, with intent to deceive and with knowledge of the statements meaning:
(1) he makes a false statement under oath or swears to the truth of a false statement previously made and the statement is required or authorized by law to be made under oath; or
(2) he makes a false unsworn declaration under Chapter 132, Civil Practice and Remedies Code. (SEE: below)

CIVIL PRACTICE AND REMEDIES CODE 132.001

(a) Except as provided by Subsection (b), an unsworn declaration made as provided by this chapter by an inmate in the Texas Department of Corrections or in a county jail may be used in lieu of a written sworn declaration, verification certification, oath or affidavit required by statute or required by a rule, order, or requirement adopted as provided by law.

37.03. AGGRAVATED PERJURY

(a) A person commits an offence if he commits perjury as defined in Section 37.02, and the false statement:
(1) is made during or in connection with an official proceeding; and
(2) is material

37.06 Inconsistent Statements

An information or indictment for perjury under Section 37.02 or aggravated perjury under Section 37.03 that alleges that the declarant has made statements under oath, both of which cannot be true, need not allege which statement is false. At the trial the prosecution need not prove which statement