Ala. Code § 17-16-42: Voter Must Answer as to Qualifications.

Any person examined as a witness may be required to answer if he or she voted at the election contested and to answer touching his or her qualifications; and if he or she was not at such election a qualified voter, he or she may be required to answer for whom he or she voted. If he or she makes full, true answers which may tend to incriminate him or her, he or she shall not be prosecuted for voting at such election.