Was Creon's decree unjust in Antigone?

Creon's decree could be said to be unjust in that it seems rather vindictive of him not to allow Antigone to bury her brother's corpse. As well as going against the will of the gods, Creon's decree seems petty and spiteful. Surely everyone must have the right to bury their loved ones, irrespective of what they've done?
Creon wouldn't see it quite like that, of course. He'd say that as Polynices was a traitor, one of the so-called Seven Against Thebes, and he doesn't think he deserves a decent burial. The fate that Creon has decreed for his corpse is a traitor's fate; it's a long-standing tradition for the dead bodies of traitors to be left to rot like this.
But it's Antigone who has the last word. She believes in the existence of a higher law: a universal sense of what's right and wrong that transcends mere earthly law. As such, she feels entitled to defy Creon's decree, even if the whole world should consider his decision to be perfectly just.