In the U.S., states can get waivers from having to comply with regulations, depending on the particular law; federal legislation is not passed as if only between some of the several states. It is pretty much a one-size-fits-all notion of federal law, with opt-outs possible typically only on particular regulatory requirements. One such publicized waiver enables states to be exempted from the health-insurance mandate if they can show they have achieved the aim (universal healthcare) by another means. Massachusetts, for example, had a pre-existing program of universal health-care.
The
complete essay is at "Unanimity as Outmoded in the E.U."
