Ala. Code § 45-20-71.15: Quorum.

The presence of the regular president and three associate members, or three associate members without the regular president or the fourth associate member, shall constitute a quorum for any regular session. The presence of all the associate members at a special meeting called without notice shall constitute a quorum. The presence of three associate members and the regular president at a special meeting after notice as provided in Section 45-20-71.14 shall constitute a quorum.