I agree, though I would say the contempt is not consciously cultivated - and one certainly doesn't become a cop if one has strong anti-establishment beliefs. Rather, I think it comes from the dissonance introduced by internalizing the 'warrior mentality' which creates a fantastical perception of the cop's reality as an endless war against unremitting criminality. In such a reality, the barriers created by "constitutional bullshit" could very well be the difference between life and death to the warrior, who is taught that they and their comrades survival is the most important goal at all times. So they come to resent such checks on their power as being imposed by clueless bureaucrats and overly idealistic citizens who don't appreciate the harsh reality of life on the battlefield.