Some police officers feel that their position in society gives them a right to treat citizens in any manner that they choose. Just because they represent the law, does not mean that they are above it. However, that does not stop some officers from verbally abusing people when pulling them over or arresting them. What the officers seem to be unaware of though is that their actions can only hurt their police work and their reputation.
These officers are under the impression that they are in some sort of action movie, and that cameras are capturing every one of their "brilliant" one-liners. In reality, their hostile behavior toward citizens is nothing short of inappropriate and is unbecoming of someone who is supposed to be serving and protecting these same citizens. These actions can make the officers seem unprofessional in front of a jury, which may detract from their statement when given in court.
These officers are often hostile in the courtroom, which Shapiro and Lozano know only too well since they are questioning these people. At times, the officers will not even show up to their depositions. That only makes them seem even more unprofessional, and gives little weight to their side of the case. These men and women are respected members of society, but that respect is earned, and can be lost as well. Like in any profession, the way you conduct yourself is of utmost importance, and that is never more so the case than in law enforcement.