The California Supreme Court has determined the answer to the question: "whether a local executive official who is charged with the ministerial duty of enforcing a state statute exceeds his or her authority when,without any court having determined that the statute is unconstitutional, the official deliberately declines to enforce the statute because he or she determines or is of the opinion that the statute is unconstitutional" is "no."
In other words, the San Franciscian mayor was wrong to supply marriage licenses to same sex couples because he felt to not do so was a violation of the state and federal constitutions. The courts have not ruled on this issue, so state law must be followed. The law itself was not examined, though I'm inclined to think the Court will eventually strike it down. The licenses handed out are void, though couples can get their money back (seriously).
The court's ruling is probably much too broad. In a case like this, when the state of the law is in flux, a state official should in various cases be allowed the discretion to follow their own judgment. [Eugene Volokh suggests this is a reasonable stance here.] They also swear to uphold the Constitution and need not be forced to wait years until a court directly determines a particular statute is unconstitutional.
The Court's parade of horribles also weren't quite to point. For instance, the Ninth Circuit recently supported a ban on assault weapons, so a local official would not have a good claim. Same sex rights are much more in flux, especially given California will likely follow Lawrence v. Texas liberally.*
As a pragmatic matter, I would support not making the licenses binding until it is determined if they are constitutionally required. It is just too messy to do so otherwise, though a total voiding is probably unnecessary. On these two points, the concurring/dissenting opinion has some good things to say.
In a weird coincidence, the Gov. James E. McGreevey of New Jersey announced today (with his wife and father by his side) that he is a "gay American" and will step down from office. As he noted: "Given the circumstances surrounding the affair and its likely impact upon my family and my ability to govern, I have decided the right course of action is to resign. To facilitate a responsible transition, my resignation will be effective on November 15th of this year."
He felt compelled to out himself because of allegations floating around, so it was a sort of pre-emptive strike. If resignation is too extreme of a solution is unclear given the details released. It's pretty sad all the same. Gay rights advocates will surely look at things in the mixed way the events deserves -- McGreevey's remarks were noble, but his actions clearly were influenced by societal prejudices, which seriously hurt not only himself, but his family and career.
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* It is ironical that a party whose most well known leader (Abraham Lincoln) was a trial lawyer would currently find it appropriate to hold that class as worthy of our disdain. The use of "liberal" as a character flaw is a bit less ironic, but not much more so. Surely, fighting against the spread of slavery to the territories (basically the reason the party was founded) was "liberal."
The much criticized Warren Harding had a pretty decent civil rights record especially as compared to his democratic predecessor. Republicans also once supported the environment (TR and Nixon), corporate regulation (Theodore Roosevelt), and fiscal restraint (various). All but the last is surely "liberal." The word has "liberty" as its base, which is not really a bad thing, is it?
On the other hand, as Legal Fiction suggests today, the Republican Party leadership seems more guided by the precepts of Lenin than any liberal principle.