The labor peace justification tries to make a virtue out of something Americans normally, and properly, despise: government by interest group. A variant of that argument, advanced by my colleague Harold Meyerson, is that ­public-employee unions, with their large campaign donations and political staffs, have become “the all-around linchpin of the modern Democratic Party” and the progressive causes for which it stands.

Some of us, though, don’t think dependence on unions has been healthy for the Democratic Party or for the robust public sector it espouses. Again, the case in point is the public schools, which employ almost half of all local government employees but which Democrats dare reform only at the risk of war with teachers unions. …

What about decent pay and benefits for low-wage workers, such as the home health-care providers in Illinois whose organization by the Service Employees International Union (SEIU) is at issue in the Supreme Court case? Actually, 40 percent of those workers opted to deduct the cost of the SEIU’s political activity from their dues, according to a review of Labor Department records by the conservative Illinois Policy Institute. That unusually high figure suggests the workers don’t think unionization is such a good deal. Obamacare has made health insurance much more widely available to low-wage workers, public and private, union or nonunion.