Any plea in abatement to an indictment must be filed at the first session at which the indictment was found, if the accused has been arrested; or, if the accused has not been arrested, such a plea in abatement must be filed at the first session at which it is practicable after the defendant has been arrested, but in all cases such a plea in abatement must be filed before the plea to the merits.
Ala. Code § 15-15-41 (1975)