If there is a complaint where the investigating officers and the prosecutor think that there is no credibility or merit to it, it would be malfeasance to take the case further. See Nifong, Mike.
Anybody can file a criminal complaint at a police station. That does not mean it will be taken further if it lacks merit.
That does not mean what you think it means though."Equal protection under the law" is a pretty explicit term. If you want to argue that some people are more equal than others, there is precedent for that.
Yes, I must be confused about the concepts of "equal", "protection" and "law". When they are strung together in a sentence, they don't actually mean that all citizens are equally protected as a matter of legal standing.