I don't know if that is suggested before, if it is, i apologize.
As some people thought like that, cops seems to be overpowered to many players because of their advantages. Especially if most of the players are playing as cops as we can see that everday, it might be boring for some players. So, that is why am i suggesting that: Limit counts of cops according to specified percentage of online players.
For instance, if there is 80 players online and we specified that percentage as %50, maximum 40 players can play as cop in the moment. It may sounds like a bad idea, but think about that, most important mission of cops is hindering criminal players with arrest or kill them. Then why would we have many more cops than criminals in the case? Think about those 80 players; if 60 players play as cops, isn't that overpowered feature of cops and doesn't that situation annoying sometimes?