Of course there can, and there always has been and always will be. The golden rule, those with the gold, make the rules. You sound like a liberal if you think justice is ever going to or has ever been applied evenly. We can certainly strive for that, but regardless of where we end up on that score, the issue of prosecuting the losers of our elections for whatever offenses the opposition (those now in power) decide to pursue is bad precedent, and I am quite happy to let Clinton, Trump, or whoever else go off into the sunset without criminal prosecution to preserve our democratic integrity.
letting politicians break the law without consequence will not preserve anything.. much less preserve "democratic integrity".