The Service Employees International Union rarely, if ever, has kept a lid on its political leanings. From 1980 through the mid 1990s under President John Sweeney, and since then under his successor, Andrew Stern, the Washington, D.C.-based union has invested enormous energy into building a progressive-Left political campaign infrastructure. There’s nothing illegal about that. Employers aren’t exactly shy about their own political machinery either. But it’s the law that the SEIU, no more than any other union, may not coerce rank and file into making contributions. And evidence suggests the union, now with some 1.9 million members, may be doing just that. The National Right to Work Legal Defense Foundation, for one, is exercised to the point of requesting a federal investigation.