http://www.scotusblog.com/case-files/cases/gill-v-whitford/ Currently, drawing legislative districts based on party affiliation is legal. This particular case questions Wisconsin's redrawing of the map by Republicans in 2011. The last time the Supreme Court saw a gerrymandering case was 2004 concerning Pennsylvania in which the Court voted 5-4 to not set a standard of what determines unconstitutional partisan gerrymandering.