>The federal government cannot constitutionally regulate sex positions, because anything not explicitly covered in the Constitution is reserved to the states, or the people.

That being said, there's probably not a constitutional way to enforce laws regulating sex positions. Even if you don't agree that such laws are clearly discriminatory in intent (let alone impact), the privacy violations necessary to prove guilt "Beyond a reasonable doubt" almost certainly violate the Fourth Amendment, and any theory of harm would implicitly (if not explicitly) rest on religion.

This is all assuming you don't accept Griswold as a reasonable constitutional argument that pretty obviously would extend to the kinds of sex people have.

> That being said, there's probably not a constitutional way to enforce laws regulating sex positions.

Right, but until someone gets arrested for this, nobody has standing to challenge the constitutionality of the law itself. It is one of those unenforceable laws. Even biblical law required witnesses (never just one) before being able to prove adultery.