Procedure
The Hall can be summoned for extraordinary meetings by the Amyrlin Seat. In addition to this, it appears that there are more regular meetings for which no specific summons is necessary.
Based on information in The Path of Daggers, it seems that most meetings of the Hall are presided over by the Amyrlin Seat; the exceptions being where there is no Amyrlin Seat, or to discuss the deposition of the Amyrlin. However, the Keeper of the Chronicles seems to act as a Chair at meetings, for example, by putting questions to the Hall and calling for votes. It is unclear to what extent this was usual practice, though; the inexperience of Egwene al'Vere as Amyrlin may have led her Keeper, Sheriam Bayanar, to take an unusually large role in proceedings. Meetings may also be Sealed this making that the only people present can be the Sitters, Amyrlin, Keeper and any witnesses, informants, accused, recognized authorities or any person(s) pertaining to the meeting.
Voting in the Hall takes place by Sitters in favour of a motion rising from their seats and remaining standing until either the required number of votes is obtained, or the chair decides that the motion fails.
On many matters, supermajorities are required. For example, a declaration of war or permission for the Amyrlin Seat to put herself in danger require the lesser consensus, which is eleven Sitters standing for the motion. There also exists a greater consensus, which is possibly a unanimous vote. It is unknown whether the Hall can decide laws and policy on simple majorities. At times meetings may be called in haste and not all members need be present, however the lesser consensus is still eleven Sitters. Examples of this happening are the impeachment of Siuan Sanche and Egwene's surrender of War Powers for the ability to be sole negotiator for rulers.
Read more about this topic: Hall Of The Tower