Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

In a 5-4 ruling, the U.S. Supreme Court upheld Arizona's independent redistricting commission in a decision that will effect similar programs of drawing congressional district boundaries in five other states and end efforts to adopt changes in other states.

Advocates of change say partisan gerrymandering by state legislatures has tied Congress in knots. Because most members are now elected from safe districts, they see no incentive for compromise, adding to congressional gridlock, the advocates say.

Fifteen years ago, voters in Arizona came up with an alternative, assigning the task of redrawing congressional district boundaries to a five-member independent commission. It drew its first map after the 2010 census.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The Arizona legislature then filed a lawsuit claiming that it had the exclusive power for congressional redistricting under the elections clause of the US Constitution. It provides that "the times, places, and manner of holding elections for ... Representatives shall be prescribed in each state by the legislature thereof."

Arizona and five other states — California, Hawaii, Idaho, New Jersey, and Washington — have each set up independent commissions to conduct their congressional redistricting.

"The lines drawn by California's Citizens Redistricting Commission have resulted in the fairest and most competitive elections in California history," said Allan Zaremberg, president of the state's chamber of Commerce.

Arizona and the other states argued that voters are the ultimate source of a state's power to make the laws, and each state "may assign its lawmaking powers in the manner it deems best." Nearly every state, they said, has chosen to reserve some lawmaking power to popular vote.

"Political sovereignty is inherent in the people, and they can assign the legislative power as they see fit," the states said, arguing that when voters enact laws at the ballot box, they are acting as the legislature, satisfying the constitutional requirement.

Writing for the majority, Justice Ruth Bader Ginsburg said the independent commissions "doubly empowers the people."

However, writing for the dissent Chief Justice John Roberts called the practice a "magic trick".

" 'Legislature' was not a term on uncertain meaning when incorporated into the constitution," Roberts wrote. "A legislature is the representative body which makes the laws of the people."