The US Supreme Court is set Tuesday to once more hear arguments on gerrymandering, the dark art of redrawing political boundaries to extract partisan advantage: a practice that is almost as old as the country itself.
The latest cases to come before the highest bench are from North Carolina, where Republican lawmakers are accused of devising electoral maps to favor themselves; and Maryland, where Democrats are accused of the same.
According to court documents, the Republican authors of North Carolina's 2016 congressional map explicitly stated their intentions.
"I propose that we draw the maps to give a partisan advantage to 10 Republicans and three Democrats," said a member of the redistricting committee, "because I do not believe it's possible to draw a map with 11 Republicans and two Democrats."
The plan was successful: in the 2018 congressional vote, Democrats won a majority of votes statewide, but only three of the 13 districts.
"A Democratic wave thus failed to breach the gerrymander's defenses," argue the plaintiffs.
The Maryland case, on the other hand, hinges on one rural district, which remained in the hands of the same Republican for 20 years. It underwent a redistricting exercise in 2012, which added more urban voters, and flipped to the Democrats two years later.
Gerrymandering came before the Supreme Court in cases related to Wisconsin and Maryland last year, but both were kicked back to lower courts on procedural grounds.
When it last considered such a case in 2004, the court voted 5-4 against reform: four judges voted unequivocally against reform, four in favour.
Judge Anthony Kennedy tipped the balance by voting against reform -- but said he might be persuaded in future if courts were presented with a "workable standard" by which to assess whether a district had been gerrymandered.
With Kennedy's retirement however, the make-up of the court has changed.
His replacement is conservative Justice Brett Kavanaugh, who was appointed by President Donald Trump last year. His position on the matter remains unknown and is eagerly awaited.
- Winning, but losing -
Under the US constitution, congressional seats are redrawn every decade during census years to account for population growth.
But the party in power at the time frequently tilts the playing field to their own advantage by processes known as "packing" and "cracking."
"Packing" involves heavily concentrating an opponents' likely voters into districts that allow them to win those areas by a heavy margin, thereby wasting every vote above the 50 percent mark.
"Cracking" goes to the other extreme, spreading the opponent's voters across districts where the favored party maintains a slim majority, thereby ensuring the losers' votes are wasted.
The portmanteau "gerrymander" was coined after Elbridge Gerry, the governor of Massachusetts, who signed a law in 1812 that created a voting district in Boston that resembled a salamander.
Though often criticized as antithetical to democratic principles, the Supreme Court has never ruled the practice is unconstitutional.
In the case of North Carolina, those responsible for drawing the map have argued it is not the court's business "to wade into the political thicket of refereeing claims that legislatures organized along partisan lines were too partisan in their redistricting".
Courts "simply do not have any business making value-laden judgments about how much politics is too much in a process that will never be free of politics," they added.
- Law and mathematics -
Ahead of the cases, a large number of lawmakers, professors and other experts writing to the court to provide expert evidence.
Forty members of the House of Representatives, both Republican and Democrat, have asked for basic constitutional limits that are easy to apply to ensure Congress can better serve the people.
Arnold Schwarzenegger, the former Republican governor of California, argued that the system creates politicians whose only competitive vote is their party primary, and are as a result more responsive to that electorate than the electorate as a whole.
"As a result, legislators often hold far more extreme views than the citizens they ostensibly represent," he wrote.
A group of law professors and mathematicians have even written to the court saying they had developed algorithms and analytical techniques that are able to dispassionately evaluate districting plans.