Should a Catholic governor veto "unconstitutional" laws?

My colleague, Gerard Bradley, has posted some thoughts about the back-and-forths going on in Kansas City between Gov. Sibelius and Archbishop Naumann.  According to the Catholic News Service:

Archbishop Joseph F. Naumann of Kansas City, Kan., said Gov. Kathleen Sebelius should stop receiving Communion until she publicly repudiates her support of abortion and makes a "worthy sacramental confession" related to her stance.

Writing May 9 in The Leaven, the archdiocesan newspaper, Archbishop Naumann said the Catholic governor of Kansas has had a long record of supporting and advocating for legalized abortion and that her public stances have "grave spiritual and moral consequences."

The column comes after the archbishop said he learned that Sebelius recently received Communion in a Kansas parish. He said he had previously met with Sebelius and discussed his concerns about her position on abortion and her vetoes of legislation to limit abortion in the state.

Archbishop Naumann told Catholic News Service May 12 that he sent a letter in August to the governor requesting that she refrain from receiving Communion because of her actions in support of abortion. He also said after discussing the issue with his fellow Kansas bishops he sent Sebelius a second letter asking that she respect his earlier request.

The Kansas City Star opined recently that the Archbishop was "scandalously" demanding that the Governor submit to "his" will.  For my own part, I don't know what the right thing -- or the canonically authorized / required thing -- for a bishop to do in these circumstances is.  Put that question aside, for a moment.  Prof. Bradley's post touches on a related matter:

. . . [Governor Sibelius] (partly) explains her vetoes as requirements of office, and not (at least not necessarily) as her own preferences.  She says that court decisions about abortion rights show that the bills cross the constitutional line, and that her oath therefore requires her to  veto the bills as unconstitutional. 

By "unconstitutional" Governor Sibelius almost certainly means: contrary to a present majority view on the Supreme Court.  But this is not the same thing as the Constitution or a sound interpretation of it.  She should not veto an abortion bill based upon what five Justices say the Constitution means, unless that is also her view of what the Constitution truly requires.  After all, she swore to "support the Constitution", not whatever a court says about it. 

Maybe — maybe — it is sometimes legitimate for a governor to veto a bill which she thinks is constitutionally sound, but which she is sure a court will strike down . . ..  But when fundamental matters of justice are at stake  — as they are with abortion  —  this won't do.

So, if Governor Sibelius holds what she ought to hold about when people begin — at fertilization — and if she glances at the Equal Protection Clause of the Fourteenth Amendment, she will see where her constituional duty lies: assuring equal treatment for all persons (including those not yet born) under the homicide laws of Kansas. 

I am not sure -- even after glancing at the relevant text -- that the 14th Amendment, properly understood, requires states to outlaw or regulate abortion.  (To say this is not, of course, to suggest that states should not regulate abortion.)  That said, I agree with Professor Bradley that it can be entirely appropriate -- more than "appropriate", in fact -- for non-judicial actors to, when exercising constitutionally conferred discretion, look to their own best understanding of the Constitution's meaning, and not simply to the latest interpretations offered by five Justices of the Supreme Court.  At the same time, I think Prof. Bradley is also right that a Governor might well decide that, for any number of sound reasons, it does not make sense to sign a law that will, given all the givens, be invalidated by a court, and thereby put the political community to (arguably) wasted effort and expense.  A question, though:  Why is it, exactly, that "this won't do" when we are talking about "fundamental matters of justice"?  I mean, even when the law at issue involves such a matter, I suppose the Governor could still reasonably conclude that, because the law is certainly, given the givens, going to be invalidated, there is no point in signing the bill.  Indeed, the Governor might worry (I'm not saying this is Gov. Sibelius's worry) that signing the bill might, by facilitating a court fight, produce further entrenchment in legal doctrine of misguided judicial precedents.  Is the idea that, when fundamental matters of justice are involved, the scandal of vetoing the bill for practical (or more thickly prudential) reasons is just too great?  Or, is it that the veto crosses the line to culpable complicity in the injustice of the acts that the Court has, mistakenly, constitutionalized?  Or something else?

Thoughts?

UPDATE:  Matt Bowman writes in with this:

You ask “Why is it, exactly, that ‘this won't do’ when we are talking about ‘fundamental matters of justice’?”  I think Evangelium Vitae 73 provides the answer.  Not the famous caveat at the end of that section, but the opening paragraph.  It says, “Abortion and euthanasia are thus crimes which no human law can claim to legitimize. There is no obligation in conscience to obey such laws; instead there is a grave and clear obligation to oppose them by conscientious objection.”  This alone shows that there is a duty preventing one from declaring that even though a pro-life law is constitutional in the pure sense (as opposed to a five-vote-majority sense), it would be a prudent thing to veto the law.  The points that precede section 73 bolster this point, so much so that I cannot list all of them.  For the reasons explained there, public officials and the rest of us have a strong duty to oppose the court-precedent “law” that legitimizes abortion.

I can anticipate at least one objection, that this command applies only to conscientious objection and not to acts of public officials.  I do not think the context allows for the separation of these concepts, since the Pope goes back and forth from this notion to the duties of the state and public officials.  Furthermore, this objection proves the point in a way.  If conscientious objection is a duty, and such objection is an exception to the ordinary norm that citizens should obey laws, how much more so is it a duty to oppose abortion-legitimizing laws in a perfectly legal and legitimate way (the executive act of signing a pro-life law), and in a way that arguably is mandated by one’s oath to uphold the constitution? 

I will not open the can of worms about why the latter part of EV 73 does not justify supposed prudential reasons to veto a pro-life law in this situation, but suffice it to say I think such an argument would be very weak and, if expanded that far, would effectively nullify all the surrounding passages of EV establishing a duty to protect preborn life by means of the law.  The main point for the present is that there is a duty to oppose abortion-legitimizing laws, signing pro-life laws is a fulfillment of that duty, the duty is so strong it requires conscientious objection, and therefore it applies to permissible acts of public officials and cannot be excused on the basis of supposed prudential objections.