A mistrial may be ordered, and in a jury case the jury dismissed, when:
Upon motion of a defendant, a mistrial shall be ordered, and in a jury case the jury dismissed, when prejudicial conduct in or outside the courtroom makes it impossible for the defendant to obtain a fair trial, or when authorized by Article 770 or 771.
A mistrial shall be ordered, and in a jury case the jury dismissed, when the state and the defendant jointly move for a mistrial.
La. Cr.P. § 775