Years 6500 to 7000 of the New Shi'ar Calendar saw the so-called alien (non-Shi'ar) races sometimes demand and subsequently rise up in armed rebellion against the New Shi'ar Imperium.  Even certain rogue members of the Shi'ar race participated in the so-called Anti-Imperial Rebellions. 

By Year 6750 (New Shi'ar Calendar), the ruling Imperial Sovereigns, thanks to wartime circumstances, had gained near-absolute powers at the expense of the Imperial Council, which became little more than as advisory assembly.

By Year 6950 (New Shi'ar Calendar), the Imperium had lost control of most of the Pocket Universe.  Year 6959 saw the Constitutional Monarchy Decree that restored most legislative powers to the Imperial Council.  Year 6998 saw the creation of the Assembly of Alien Races, which at first had only advisory powers, but it gave representation to members of non-Shi'ar races.