I suspect that your estimate that 90% of cops are good is a tad high. Based on what we have seen
over the past 10 years, bad and illegal behavior by cops is way up so I think the there are 
more bad apples than you think and it does not take many to spoil the barrel, especially when
the so called good cops look the other way and do nothing when they see a cop who is out of
control and then claim they saw nothing when things like what this cop did to the nurse comes
to light.