I see what you are saying, lugsoul, but, and correct me if I'm wrong, but wouldn't this be a state by state vote, each state deciding whether this was or was not acceptable law, and is that not federalism.
Ummm, no. Because states that voted against the Amendment could still have it forced upon them. That is, their definition of marriage - or, more directly, who is entitled to the "legal incidents" of marriage - would be controlled by Federal, not state, law.