The police won't be affected by the changes, they can retire as soon as 52 y.o.
In the past few years they lowered the standards of the academy. If a police trainee has a history of domestic violence, anger issues, DUI, they can still become full fledged members of the police. At worst they might have to repeat a year, very few of them are actually fired from the academy.
So, you have a rising amount of unstable individuals with authority and weapons, who are not affected by the new law, and they know they won't get punished for beating up citizens.