Texas Code of Criminal Procedure - CRIM P Art. § 46C.151. Determination of Sanity Issue by Jury

(a) In a case tried to a jury, the issue of the defendant's sanity shall be submitted to the jury only if the issue is supported by competent evidence. The jury shall determine the issue.

(b) If the issue of the defendant's sanity is submitted to the jury, the jury shall determine and specify in the verdict whether the defendant is guilty, not guilty, or not guilty by reason of insanity.