A preliminary ruling in a redistricting case from Pennsylvania
A state constitution is a state constitution, which is not the federal Constitution.
There's a lot going on with gerrymandering challenges in the Supreme Court. But let's get one thing straight: several redistricting cases are based on the U.S. (federal) Constitution, and this one out of Pennsylvania is not.
The Pennsylvania case
The Pennsylvania Supreme Court ruled on January 22, 2018 that Republicans had unfairly drawn the state's voting lines. The PA high court ruled the drawings could not satisfy the Pennsylvania State Constitution because they were drawn to Republican favor, so the court ordered the PA legislature to redraw the map.
Because the ruling was based on Pennsylvania law (not federal law), the Republicans needed a different federal law argument to get the case appealed to the Supreme Court. In regards to Pennsylvania law, the case had already reached the top.
The Supreme Court request
The Republicans found their federal law argument in the Elections Clause of the U.S. Constitution. They asked the Supreme Court to put the PA Supreme Court order (to redraw the lines) on hold until they could file their Supreme Court appeal. But Justice Alito, who is responsible for hearing emergency appeals from Pennsylvania, did not find the Elections Law argument compelling enough. He refused to put the PA order on hold. So PA's legislature will be redrawing the lines.
Redistricting cases under federal law
The Supreme Court has agreed to hear two political redistricting cases so far this term (out of Wisconsin and Maryland). Each of them is based on the federal Constitution, but on different provisions of it. The third political redistricting case that has made an appearance has not yet been accepted for review, but the Court has indicated its interest in the case. That one comes out of North Carolina. It is also based on federal law. When the Republicans filed for an emergency stay in the North Carolina case, they won: the NC legislature will not have to redraw NC lines until the Republicans have their go in the Supreme Court.
Political versus racial gerrymandering
All four of these cases are challenges to political gerrymandering. Yet there is a racial gerrymandering case out of Texas that the Court will be hearing later this term. See our infographic on Gill v. Whitford for a note on the difference between racial and political gerrymandering.