Since the purpose of all Law is "Justice" and "Justice" is a Virtue---the "Queen of Virtues" actually, it is ridiculous to "think" that "Just Laws" are NOT moral law. Our country was founded on Universal Truth. Our Jurisprudence on the ideas that we have unalienable Rights from God (Universal Truth). So, to argue that there is no morality in U.S. law is irrational.
All laws, if they are Just Law, have to promote Justice (Virtue). Laws that promote Vice (like sodomy) are unconstitutional because they force the idea that Evil is Good. You can not use other human beings as a "means to an end" in Christian Ethics which is embedded.
Can't have that in America. It warps all relationships to a sick, unnatural, immoral worldview of Satan.