I'd like mine fully baked, please ...

Law prof Jason Mazzone dislikes DOMA, but, perhaps due to Justice Roberts' high stakes pressure of Justice Kennedy, recommends an O'Conner style approach, narrowing the basis of the decision until it becomes uncontroversial, thus enabling a proper and non-ideological decision.  Problem is, his arguments need a bit more time in the oven.

Mazzone first asserts that the federalism argument is weak because the federal government has already involved itself so heavily with marriage, as it doles out so many benefits on the basis of marital status.  Yet this enitrely misses the point of the federalism argument.  The federalistas are not concerned with the states' authority to hand out governmental blandishments, but rather with the states' authority to sanction and regulate marriage.  When I got married, we went down to the old Santa Barbara courthouse, answered questions asked by the State of California, and got a piece of paper stamped by the State of California telling us we could tie the knot - the feds didn't have anything to do with it, and that's the point.  I could be wrong here, but I believe that DOMA is the only standing federal law that purports to discriminate not between married and unmarried citizens, but between different "types" of marriages, asserting that for purposes of federal benefits, etc., some marriages are valid and other marriages are not, regardless of whether they have been duly sanctioned by state law.  Regardless of your feelings about federalism and its effect on the outcome of the case, the federalism argument is a serious argument here.  The feds may use marital status in many ways, but they have never seriously attempted to assume the authority to determine marital status in the first instance, and I don't see it as at all clear that they can.

Mazzone's second assertion is that the challenge should not be to DOMA itself, nor to the ~1100 other federal statutes implicated by DOMA, but rather only to the specific section of the tax code that harmed the plaintiff.  This doesn't even pass the sniff test.  The tax code does not purport to define the plaintiff out of the covered class; DOMA does that.  She clearly has standing to challenge DOMA, and if it is unconstitutional its effect on those 1099 other statutes is clearly improper.

There may be ways to limit the scope of a ruling and make it more palatable, and the court may even adopt Mazzone's.  They are, however, pretty transparently half-baked.