The COMPNOR Political Aasembly was created in 1 ABY to replace the now-defunct Galactic Senate which had existed under both the Galactic Republic and for years under Palpatine's Galactic Empire. The Senate, an elected body elected by sector assemblies in turn elected by local populations or appointed by planetary governments, was dissolved permanently in 0 ABY because some senators covertly supported the Rebel Alliance.
The COMPNOR Political Assembly was appointed by the Select Committee, which led the Commission to Preseve the New Order, a leading non-military branch of the Imperial government. After the Battle of Endor in 4 ABY, the COMPNOR Political Assembly was officially dissolved.
In 50 ABY, in the Imperial Remnant under the rule of Emperor Jagged Fel, both COMPNOR and the COMPNOR-appointed Political Aasembly were reestablished to provide ordinary Imperial citizens with a voice in government.