When it comes to Washington politics, the old rules of cause and effect don’t seem to apply, at least not in a logical way. They never really did, to be honest, but the rules of engagement keep bending ever further from the pull of common sense. For years, leaders in Congress have debated, sparred and battled over trying to reform and revise the nation’s immigration laws to — depending on the focus of the particular legislation — tighten the borders, create a legal path for millions of illegal migrant workers in the U.S. or both, in some combination.