My favorite thing about it is this the more you watch cop shows and cop movies the more you notice a pattern. The biggest villain for all of those shows, the most consistent threat? Internal affairs. It's like every single movie and every single series it has shown up at least once. Those God damn Internal Affairs people stopping good cops from doing what they need to do. It's maybe the single strongest trend throughout all of these shows and movies.
Hell it was even a plot point in Psych. The show about fake psychic detectives had a bad guy Internal Affairs officer.
If only Stabler could have freely roughed up every single suspect, they might have caught a couple of the rapists sooner. Probably would have got some coerced confessions out of some creeps who were destined to rape in future too.
This is why I say the Wire is the best cop show out there still, espevially growing up with a cop. It raises up the parts of police work that deserve praise; eg. the individuals that get in for the right reasons or have appropriate respect for the job once there, the opportunity police have to make a positive impact on outliers in our society, etc. It also gives a pretty realistic look at how these things go wrong or become ineffective at an institutional level (and 100% don't shy away from idiot/aggressive cops, narratively equating them to gang members). As far as I can remember there is never a "big, bad internal affairs" plot line. When it does come up it's in reference to a character's problematic behavior and treated as a fair consequence of their actions.
Watch the Wire if you havent and you like crime-drama. It's as good as it gets.