Just as Roe v. Wade legalized abortion on demand throughout all 9 months, so would another potential court ruling. Look how impossible it has been to overturn Roe v. Wade since the legal atrocity occured. The Federal Marriage Amendment - co-authored by THE strict constructionist Judge Robert Bork - would have protected states from such a ruling as it pertains to gay marriage/domestice partnerships/civil unions. Giuliani strongly and vocally opposed the Federal Marriage Amendment.
so long as the defense of marriage act holds - the amendment is not needed.
if an activist SCOTUS tosses the DOMA, then its a different story.