The U.S. Supreme Court failed to reverse a 200-year-old assault on the rights of the American voter Thursday in its regrettable decision upholding the corrupt practice of gerrymandering.

In 5-4 decisions in two cases, the court opted not to block the practice of drawing voting district lines to favor one party over another. The cases had challenged congressional maps in North Carolina and Maryland. The majority ruled it was not up to the courts to put limits on a political party in power from manipulating the boundaries of electoral maps.

The North Carolina plan, drawn by Republicans, helped the party capture a disproportionate 10-3 majority of that state’s congressional House districts. In Maryland, a single congressional district drawn by Democrats resulted in that seat being won from a Republican incumbent.

All the justices agreed such tactics are abusive and damaging to the democratic process, but the majority claimed it could do nothing about it.

“We conclude that partisan gerrymandering claims present political questions beyond the reach of the federal courts,” Chief Justice John G. Roberts wrote in the majority opinion.

This claim that the courts are powerless to protect the integrity of the vote ignores the fact that lower courts, in striking down multiple partisan redistricting maps, have produced a formula for doing just that, noted Justice Elena Kagan, writing the dissenting opinion.

Lower courts have proposed a three-pronged test. To prevail, a plaintiff would have to prove that lines were drawn to protect entrenched party interests. Second, that the result diluted votes. And, third, that there was no nonpartisan explanation for the district boundaries.

This test, which should have been adopted by the Supreme Court, would have allowed the courts to block abuses and put politicians on notice they had better draft district boundaries that were at least remotely fair.

Instead, as Kagan, noted, the court surrendered to political corruption.

“In the face of grievous harm to democratic governance and flagrant infringements on individuals’ rights — in the face of escalating partisan manipulation whose compatibility with this nation’s values and law no one defends — the majority declines to provide any remedy,” Kagan wrote.

The majority has done the nation and the Constitution an injustice. The timing of the ruling is especially damaging because it coincides with the 2020 U.S. Census survey. The Constitution mandates a national census be conducted every 10 years and new congressional and state voting districts be drawn to reflect population shifts.

Thursday’s ruling might as well have declared open season for state legislatures to engage in more extreme partisan shenanigans when redrawing the electoral maps in 2021.

Gerrymandering is an art of political chicanery as old as the nation. Gerrymandering is named for Elbridge Gerry, who became governor of Massachusetts in 1810. Gerry presided over the 1811 drawing of his state’s voting districts to favor his ruling party. Recent computer-assisted advances in demographic data gathering have ushered in an era of sophisticated and flagrant mapping manipulations that effectively disenfranchise the votes of many Americans.

Republicans have played a particularly masterful game of drawing congressional districts to their advantage. Republicans control 30 state legislatures and dominated the electoral district map configurations in 2001 and 2011.

State legislatures in 42 states, including Connecticut, control the drawing of the political maps the first year of every decade. Eight states — Alaska, Arizona, California, Colorado, Idaho, Michigan, Montana and Washington — have independent bipartisan commissions to map their congressional and state legislative districts.

Given this decision, it is left to citizens to demand that more states, including Connecticut, adopt bipartisan commissions to draw district lines so that everyone’s vote counts equally.

Chief Justice Roberts began this year’s Supreme Court term by pledging that the justices would not “serve one party or one interest.”

“People need to know we’re not doing politics,” Roberts said. “We do not have Obama judges or Trump judges, Bush judges or Clinton judges.”

That may be true, but the Supreme Court is composed of five conservative judges, including Roberts, chosen by Republican presidents and four liberals nominated by Democrats. Despite Roberts’ claim that his court “does not do politics,” Thursday’s vote was a politically consequential decision.

The four liberal jurists who voted to strike down the Maryland and North Carolina maps — Kagan, Sonya Sotomayor, Ruth Bader Ginsberg and Stephen G. Breyer — focused on individual voting rights. The conservative judges in favor of upholding the gerrymander — Roberts, Brett M. Kavanaugh, Neil M. Gorsuch, Clarance Thomas and Samuel A. Alito — found a justification for inaction that disproportionately benefits Republicans.

America’s political divide is stark and pervasive. Allowing gerrymandering adds energy to that corrosive political chasm.

The Day editorial board meets with political, business and community leaders to formulate editorial viewpoints. It is composed of President and Publisher Timothy Dwyer, Executive Editor Izaskun E. Larraneta, Owen Poole, copy editor, and Lisa McGinley, retired deputy managing editor. The board operates independently from The Day newsroom.