When it comes down to it, morality rests upon the enforcer. "I am just following orders" is the battlecry of many oppressive, anti-humanitarian forces throughout history. It's a certain type of evil to give the order to oppress someone, but the actual evil isn't manifested until someone, well, manifests it. It's the difference between thinking about killing someone and actually doing it.

If the legislatures want to write laws to oppress people, but won't do it themselves, they're just evil, hypocritical cowards. If a person goes against their conscience and better judgment and enacts the unjust order, they are ultimately the more guilty party.

Of course, there is an argument to be made, what with IQ ceilings placed on who can be a cop, that the enforcers aren't smart enough to recognize morality.