From Will Saletan at Slate:
the tricky thing about official intervention is that once the state gets its foot in the door, you don't necessarily get to dictate what it can and can't do.
He's talking about how "For the usual incoherent combination of lefty reasons—not enough private discrimination in working conditions, too much private discrimination in family values--" he "felt the urge to support regulation of the [surrogate motherhood] industry," but then he read about Chinese police kicking in doors and forcing surrogate mothers to abort their babies, and realized that wasn't "the kind of policing liberals have in mind when they call for tighter regulation of the fertility industry."
But the lesson is broader, of course. It applies to health care, education, energy, faith-based organizations, and just about any enterprise you let the state take a role in.