I agree with what you are saying but I think many who would sign this petition don't want systematic legal changes for human rights, they want law enforcement to have a free hand to pressure with plea bargaining, profiling, torture, oppressing certain minorities, and generally police state powers to protect "us". What they want is preferential protections to better differentiate us vs. them and for "us" not to be caught in an oppressive legal system. Someone might identify with Aaron but not with a Troy Davis, who was executed in Texas based on false evidence. So maybe a petition makes more sense for such people.