Was this based on the state or federal constitution?
State Constitution. Haven’t read the whole opinion yet, but in discussing the separation of powers they do say that “the power of the constitution flows from the people, and the people of Iowa retain the ultimate power to shape it over time.”
To me that means they are saying that if the people amend the state Constitution banning gay marriage, they will be bound by that amendment.
“Was this based on the state or federal constitution?”
In theory this can’t be based on the Federal Constitution since marriage is strictly a state issue. Marriage is not mentioned in the Constitution. On the other hand, far be it from leftwing judges to find rights in the Constitution that don’t exist.
Ironically, the right to license is the right to deny. If a license can be had by anyone who wants it, then there is no purpose to a license. I bet you can’t get a plumbers license in Iowa unless you are a plumber. Isn’t that discrimination against non-plumbers who want to lay pipe?