Liberals often like substantive federal law. As compared with state legislatures whose interests they sometimes regard as parochial or even retrograde, liberals tend to favor the United States Congress as a forum for enacting what they view as progressive ideas into law. (Think of the drive for civil-rights legislation in the 1960s, or for gun-control or patients’-rights laws more recently.) Conservatives, by contrast, usually don’t like federal law. From their standpoint, the federal structure enshrined in the Constitution protects individuals from a potentially tyrannical national government by limiting the scope of federal substantive law and respecting the primacy of state governments, which are obviously closer geographically (and often philosophically) to their citizens. Yet while liberals and conservatives disagree about the optimal scope of federal substantive law, there is one view they seem to share: a thoroughly skeptical view of federal jurisdiction – or, at least, federal removal jurisdiction, which is the subject of this essay....