The Reconstruction-era case of United States v. Klein remains the object of a “cult” among commentators and advocates, who see it as a powerful separation of powers precedent. In fact, Klein is a myth—actually two related myths. One is that it is opaque and meaninglessly indeterminate because, given its confusing and disjointed language, its precise doctrinal contours are indecipherable; the other is that Klein is vigorous precedent, likely to be used by a court to invalidate likely federal legislation. Close analysis of Klein, its progeny, and past scholarship uncovers three identifiable core limitations on congressional control over the workings of federal courts. But close analysis also reveals that these principles are neither exceptional nor vigorous as judicial constraints on congressional power. It is telling that in 140 years, Klein has not been used to invalidate any actual legislation, other than the law at issue in Klein itself. At bottom, Klein becomes the lynchpin for constitutionalizing basic policy preferences against these laws. But this ignores a central distinction between bad policy and unconstitutional policy; we cannot confuse what the Constitution prohibits with bad statesmanship. Couching policy objections in Klein terms does not make the decision any less a constitutional myth.