The Freedom to Own Slaves?

Prof. Dale Carpenter points out that St. Thomas University School of Law Professor Robert Delhunty is using a slavery analogy to argue (implicitly) in favor of a constitutional amendment banning same-sex marriage in Minnesota. Prof. Delhunty's premise is that whenever one party gets freedom, the freedom of another party is necessarily constricted:

[W]henever the law expands the freedoms of one person or group, it necessarily contracts those of another. When the U.S. Supreme Court raised the bar to success in libel suits brought by public officials, it expanded the freedom of the press but diminished the freedom to serve in public office without fear of being defamed. Freedom to publish narrows the right to safeguard a reputation.

Fairly cogent points. But, alas, he goes on:

[T]he constitutional amendment banning slavery necessarily ended the freedom to own slaves. But it is not an argument for that amendment that it expanded freedom without contracting it. It did both. 

It is rare, but perhaps occasionally wonderful, to see an argument reduce itself to absurdity. Prof. Carpenter breaks it down:

So slaveowners lost what Delahunty calls a “freedom” — “the freedom to own slaves” — when they were forced to live in a world where they could no longer own slaves. It’s just that slaves gained more freedom from their freedom than slaveholders lost from losing the freedom to own other people.

I am going to put this in the bottom ten percent of arguments I've seen against same-sex marriage.