Cops and politicians no. We have to hold them to a much higher standard if we are going to authorize the power we give them. The Sword of Damocles must hang over all their heads. We don't put a high enough price on power.
I vehemently disagree. Human rights, including the right to being presumed innocent until proven guilty, should not be waived because of someone's occupation.
The problem of guilt being difficult to prove is one that extends far beyond just police or politicians; it applies to anyone accused of committing a crime, and it means that we know that we allow some of those guilty of crimes, even heinous ones, to walk free. We have made a lot of progress in that area, and will continue to do so. It is appropriate to introduce new technology, procedures, or policies that can help make it more difficult for people to hide their guilt, but at the end of the day, a policeman is a man and deserves the same protections that you or I do.