The Supreme Court has agreed to hear two important cases where the deliberate drawing of congressional district lines involved giving one side a partisan political advantage.

It's known as "gerrymandering," and it's supposed to be illegal.  The court may determine ground rules for when politics intrudes too much in drawing district lines.

The Hill:

The justices, however, have long wrestled with how to measure when partisanship in the redistricting process has gone too far.  The cases present a fresh opportunity for a state map to be struck down as an unconstitutional partisan gerrymander for the first time.

In the Maryland case, state Attorney General Brian Frosh (D) is appealing a district court ruling that requires the state to redraw its 2011 congressional redistricting plan before the 2020 election after a district court found state officials intentionally flipped control of the 6th Congressional District from Republicans to Democrats.

In the North Carolina case, Republican lawmakers are appealing a 2nd District Court ruling striking down the state's 2016 congressional maps. The decision stemmed from a challenge brought by Common Cause and the League of Women Voters alleging the maps were drawn to give Republicans a partisan advantage.

The court said arguments will be set for March, which means a decision will likely come by the end of June. It takes four justices to agree to hear a case.

Last term, the court sidestepped the issue in the Maryland case and in a case out of Wisconsin.  In the Wisconsin case, Democratic voters alleged Republican legislators had unfairly and strategically put them at a disadvantage.  But in a narrow ruling, the justices said the voters lacked standing to challenge the state's entire map and remanded the case back down to the lower court.

The origin of the word "gerrymandering" goes back to the early 19th century:

[It's taken] from the name of Governor Elbridge Gerry of Massachusetts + salamander, from the supposed similarity between a salamander and the shape of a new voting district on a map drawn when he was in office (1812), the creation of which was felt to favor his party.

In truth, America has a long, troubled history when it comes to gerrymandering.  When blacks got the right to vote, district lines were deliberately drawn to weaken their power.  Hence the Civil Rights Act, which required all Southern states to submit their redistricting plans to the Justice Department. 

But the sort of gerrymandering the court will take up involves the party in power in the state legislature drawing lines that give them maximum advantage.  It's a relatively simple matter these days.  With sophisticated computer programs and access to census and other historical election data, the computer will do all the work for you.  That's why many district lines look as if they were drawn by a drunk chimpanzee.

Both parties are guilty of it, and it's going to be tough for the court to determine how to judge if redrawing congressional districts is "too partisan."  It may be that inputting certain demographic information into a computer program might yield less partisan results, but there's really no guarantee of that.

These difficulties may force the court to once again decide the issue narrowly, addressing only the cases before it.