Code of Alabama
Division 2 - Competency.
Section 12-21-165 - Incompetent Witnesses.

(a) Persons who have not the use of reason, such as idiots, lunatics during lunacy and children who do not understand the nature of an oath, are incompetent witnesses.
(b) The court must, by examination, decide upon the capacity of one alleged to be incompetent from idiocy, lunacy, insanity, drunkenness or infancy.