There have been riots and the police is widely unpopular. Private police departments have started to appear to take things in their hands. Although the government has no way of making those illegal, they regulate it by having a sort of bar code in cops' ID and uniforms, without which nobody is allowed to enter certain areas or arrest people (that last point is a major cause of trouble). Since it's not that hard to get cops uniforms either, they go as far as to register every cop in an ocular data base. Yes it's looking more and more like a dictatorship. That's because of a game of action-reaction and blatant bad behavior from everyone.
This morning, a police station received two calls; one about a drug cartel causing trouble, that the station was told to ignore as "false flag", the other a short moment later about a suspicious gathering in the same troubled neighborhood. They immediately sent 3 guys.

Well these almost immediately got captured. "Don't fight back, an authoritative voice said, it's over. Just do what you're told and we won't hurt you. Get in the van." The captors are used to it. Cops are not that motivated with what they're told to do by their hierarchy either, and unlikely to risk their lives too much when in danger. So the guys just did as they were told by their captors. They had to strip down and let themselves be cuffed and have their mouths duct taped shut. Then the captors put on their uniforms and roughed the guys up, hustling them out of the van again and to a back alley where they were sat down.
"Don't take it personal guys, the same voice said, I guess you're okay guys. Again sorry about that eh, now listen up. Take it easy, just wait for something to find you, and most important: don't tell anyone you're cops."

Now they'll have to also take the ocular print, so they can, you know, go after the drug cartel and be allowed to do something about it.
"Gee someday they'll put chips in cops' brains and we'll have to carry around these meat bags all the way with us," one alt-police sneered.
"Impossible, they don't have brains!" another said...

Not only is the ocular printer pretty effective, it also has the advantage of putting them to sleep nicely