Here's something I was thinking about over the weekend. The Supreme Court's decision that the federal government can't threaten to cut off existing Medicaid payments to states that decline to expand their Medicaid programs is clearly conservative in its immediate result. This is going to encourage states to decline Medicaid expansion and thus limit the scope of overall transfer payments to poor people.
But is there anything conservative about the general principle?
I'm not sure that there is. After all, the basic technique congressional Democrats used to get the job done could be applied in pretty much whatever way you wanted. Suppose John Boehner started demanding a law that states will lose existing Medicaid funding unless they adopt fetal pain laws. Indeed, one element of Mitt Romney's education plan (PDF) is to "require states to adopt open-enrollment policies for students receiving Title I and IDEA funds, and to eliminate caps on charter and digital schools." That seems like a good idea to me, but it seems like a consistent application of the new spending power principles would render it unconstitutional. The Romney administration wouldn't be allowed to coerce states into changing their charter-school laws by threatening their existing Title I and IDEA money; they'd have to rely on a carrot strategy as the Obama administration did with its Race to the Top grants. So that's a nice win John Roberts just tossed to teachers' unions and other charter-school skeptics.
Now, of course, the Supreme Court is not bound by precedent, either in theory or in practice, so there's no guarantee the new principle (which seems just made up with no basis whatsoever in the text of the Constitution) would actually be applied in this way, but most commentary I've seen on this issue does assume the precedent will stick and be applied in other circumstances. But as a general matter, I'd think liberal members of Congress will be much more comfortable than conservative ones with a world in which all efforts to change state policy have to be done via the carrot of new money rather than the stick of jeopardizing old money.