It’s only un-Constitutional if you accept that FedGov has ANY authority to legislate in this subject.
Hint: They DON’T.
This is a State’s Rights issue.
States Rights? The purpose of the States is to help divide up the work of administering the Federal Government’s edicts, plus the State names help the NSA keep track of what they’re spying on.
Unfortunately while we’re worried about State’s rights the Obama administration is working hard on yielding our national sovereignty to the United Nations through various treaties.