The Athletic Union's Constitution contains the set of governing rules and principle that the organisation must follow. It provides members, Club Committees, Athletic Union Executive Officers, the Sport E.O. and staff with an operational framework to develop and run the AU. The Constitution basically describes how the AU works and how it makes decisions.
A copy of the constitution can be found on the AU website  and as stated in the constitution, changes to the constitution can be passed at Athletic Union General Meetings.