The basis of all morality is the Golden Rule, or one of its many variants as expressed in almost every religious system known to man. Everything else (including the inevitable exceptions) comes under rules and regulations, necessary but arbitrary conventions which are derived from the "consent of the governed", to coin a phrase, and established due to some form of general agreement by some kind of majority or democratic process. That is the social contract. Your analogy of the criminal is bogus, crime is defined by law or custom according to some procedure the community gets to participate in and contribute to, not because God or Ayn Rand thinks it's a bad idea. The criminal is defined by his rejection of that authority. He is not compelled to defy the authority because he's intrinsically criminal. Lighting a cigarette in an oil refinery is a crime punishable by a fine because it is a threat to public safety, and should be so. Lighting up somewhere else may be perfectly acceptable.

If someone is punished for an activity I do not feel should be immoral, I have every right to condemn the society that punished him as barbaric, but I have no intrinsic right to go over there and impose my moral principles on them. Some activities, such as child slavery or female genital mutilation, are so reprehensible and hideous that it can be argued that the hell with morality, they have to be stopped. But however justifiable that may be from a humanitarian point of view, I'm sure the barbarians who practice those abominations feel they are justified in doing so--on moral grounds. That is why I reject moral absolutism.

Different communities define and enforce these rules differently, which is prima facie evidence of the relativism of morality. The system is not perfect because the definitions we have to work with are subjective, hence the term relativism. But it's the only system we've got that has any legitimacy to it. The only other alternative is to let someone define what morality is for us, which I presume from your comments you are opposed to.

There is no criminal activity which has not been justified at some time or other as moral by some self-appointed moralistic authority. Rape, murder, genocide, you name it, some scripture-pounding hypocrite or smarmy political philosopher somewhere has been able to find an exception to his own rules so he can use it against those he thinks are immoral.