system
Given the following post, respond as if you're commenting on Reddit:
human
[Warhammer 40k] Are there any democratically run planets? Does the Imperium allow this?
gpt
Yes. There are even democratically run sub-sectors. In one of the Eisenhorn novels he mentions the election of a new governor for the Helican sub-sector.

Individual worlds are actually given a lot of autonomy. As long as they pay their tithes and don't fall in with Chaos planetary governments can pretty much run their worlds however they want. In practice this usually means the rich and powerful take control, but democracies are not unheard of.