WASHINGTON (Reuters) - The U.S. Supreme Court is giving itself another chance to make a definitive ruling on the legality of the long-established but often-criticized political practice called partisan gerrymandering in which state legislators draw electoral districts with the intent of entrenching their party in power.

FILE PHOTO: Demonstrators rally in front of the Supreme court before oral arguments on Benisek v. Lamone, a redistricting case on whether Democratic lawmakers in Maryland unlawfully drew a congressional district in a way that would prevent a Republican candidate from winning, in Washington, U.S., March 28, 2018. REUTERS/Joshua Roberts/File Photo

The high court, which failed to resolve the issue last year, on Friday agreed to hear constitutional challenges to electoral maps drawn by Republicans in North Carolina and by Democrats in Maryland. The court will hear arguments in both cases in March, with rulings due by the end of June that could have enduring political consequences nationwide.

Critics have said partisan gerrymandering is becoming more extreme with the use of precision computer modeling to the point that it has begun to warp democracy in certain states by subverting the will of voters.

The high court has struggled over what to do about this practice in which boundaries of legislative districts are reconfigured by state lawmakers with the aim of making them friendly territory on Election Day for candidates in the party in power at the expense of opposing candidates.

The justices in June 2018 failed to issue definitive rulings in cases from Wisconsin and Maryland that election reformers had hoped would prompt the high court to crack down on partisan gerrymandering.

In the North Carolina case, Democratic voters accused the state’s Republican-led legislature of drawing U.S. House of Representatives districts in 2016 in a way that disadvantaged Democratic candidates in violation of the constitutional guarantee of equal protection under the law. A lower court sided with the Democratic voters.

“Partisan gerrymandering in North Carolina has become so pervasive that the outcome of many elections is decided before a single vote is cast,” said Janet Hoy, co-president of the League of Women Voters of North Carolina, which challenged the state’s map.

In the Maryland case, Republican voters accused Democratic legislators of violating their free speech rights under the Constitution’s First Amendment by redrawing boundaries of one particular U.S. House district to hinder Republican chances of winning. Democratic legislators in 2011 removed Republican-leaning areas and added Democratic-leaning areas to the district, which had been held by a Republican congressman but has been won by Democrats in every election since.

Democrat David Trone won the seat in November’s election.

Slideshow ( 2 images )

After the Supreme Court in June sidestepped a ruling on the merits of the case, a three-judge panel threw out the district in November as violating the constitutional rights of voters.

“It is our view that Supreme Court review is needed to provide guidance to the legislature in future redistricting,” said Raquel Coombs, a spokeswoman for Democratic Maryland Attorney General Brian Frosh.

TWO CENTURIES OF GERRYMANDERING

Gerrymandering is a practice dating back two centuries in the United States. While the Supreme Court has ruled against gerrymandering intended to harm the electoral clout of racial minorities, it has never curbed gerrymandering done purely for partisan advantage. A definitive ruling could reverberate through American elections for decades by either endorsing the practice or curbing it.

The court has repeatedly failed to devise a practical standard for judges to use to resolve claims of partisan gerrymandering and, in resolving the new cases, it could decide that one does not exist.

The Supreme Court in November agreed to hear in the coming months another gerrymandering case, one based on allegations that Virginia Republicans unlawfully diluted the clout of black voters when drawing state House of Delegates districts.

The composition of the high court, which has a 5- conservative majority, has changed since its last gerrymandering decisions. Conservative Justice Anthony Kennedy, who sometimes sided with the liberal justices in major cases, retired and was replaced by President Donald Trump’s appointee Brett Kavanaugh in October.

In a 2004 gerrymandering case, Kennedy wrote a concurring opinion that left the door open for courts to intervene if a “workable” standard for identifying and measuring impermissible gerrymandering could be devised. It remains to be seen what Kavanaugh will do with the issue.

Legislative districts across the country are redrawn to reflect population changes contained in the nationwide census conducted by the federal government every decade.

This redistricting in most states is carried out by the party in power, though some states assign the task to independent commissions to ensure fairness. Gerrymandering typically involves packing voters who tend to favor a particular party into a small number of districts to diminish their statewide voting power while dispersing others in districts in numbers too small to be a majority.

Democrats have said partisan gerrymandering by Republicans in several states helped Trump’s fellow Republicans maintain control of the House and various state legislatures for much of the decade, although Democrats seized a majority in the House in the November elections and made inroads in state legislatures.