A new Supreme Court term begins Monday. On Tuesday, the court will hear arguments i n Gill v. Whitford, otherwise known as the “Wisconsin gerrymandering” case. This is one of the most anticipated showdowns that the Justices will be expected to referee in coming days and weeks. Constitutional lawyers in the U.S. distinguish sharply between racial and partisan gerrymandering. When the claim before the courts is that lines were drawn to bleach certain districts, keeping racial minorities out, then the courts want to see proof that this was indeed the predominant motive. Not just a motive, but the predominant motive. Plaintiffs do overcome that burden, as we saw for example in a Supreme Court decision just last term. When the lines are drawn for the sake of advantaging one political party over another, though, the Supreme Court hasn't quite known how or whether to respond. In one case on point 13 years ago, Vieth v. Jubelirer (2004) the court split 4 to 1 t...