U.S. Rep Martha McSally stands to benefit if the Supreme Court limits Independent Redistricting Commission authority.

PHOENIX — Fearing defeat at the Supreme Court, more than a dozen members of Congress from California and Arizona introduced legislation Friday to preserve congressional boundaries set by independent redistricting commissions.

HR 2501 bars the legislatures in six states, including Arizona, from redrawing the lines ahead of the 2020 decennial census. That preserves the current political balance of power of each state’s congressional delegation.

The high court could rule as early as Tuesday on a challenge to the authority of the Arizona Independent Redistricting Commission to craft congressional districts.

That lawsuit, brought by Republican legislative leaders, points out the U.S. Constitution gives each state’s legislature the power to determine the “times, places and manner” of congressional elections. What that means, they contend, is Arizona voters had no legal right to give that authority in 2000 to the five-member commission.

A decision in favor of the challengers would pave the way for Arizona’s Republican-dominated Legislature to redraw the lines in a way more favorable to GOP candidates.

At the very least, that likely would mean putting more Republicans into the Southeastern Arizona congressional district to firm up support for Martha McSally. She ousted Democrat Ron Barber last year by just 161 votes out of more than 219,000 cast.

But it also would provide an opportunity for the Legislature to tinker with other districts to undermine support for incumbent Democrats, particularly Ann Kirkpatrick.

The ruling, though, would have impacts beyond Arizona, as five other states have some sort of similar arrangement. That’s why HR 2501 is crafted to protect their congressional delegations, too.

Rep. Alan Lowenthal, D-Calif., one of the prime sponsors of the legislation, acknowledged it is just a stopgap solution. Absent further action, it would allow each state’s legislature to take back the power to draw congressional lines after the next census.

But Lowenthal said this incremental approach is by design.

“The plan is not to make people in Congress who are nervous about this more nervous,” he said. “The plan is to do it as we move forward and there’s a real opportunity for people to act in a rational way.”

And that “rational way,” Lowenthal said, means taking away the power of politicians to draw their own political boundaries. Lowenthal, who previously served in the California Legislature before that state had an independent redistricting commission, called that a “most offensive process.”

The fight turns on the constitutional provision saying the method of choosing members of Congress “shall be prescribed in each state by the Legislature thereof.” That’s the way it occurred in Arizona before 2000, a process that often resulted in districts designed to give an advantage to the majority party.

That year, however, voters amended the Arizona Constitution to create the five-member commission, charging it with drawing both legislative and congressional lines.

Republican legislative leaders sued only after new districts were drawn following the 2010 census, when the state got another seat in the U.S. House. Those lines initially give Democrats five of the nine seats; McSally’s election last year made the delegation 5-4 Republican.

During court arguments in March, Paul Clement representing the GOP leaders, told the justices the constitutional language is absolute.

“This avowed effort to redelegate that authority to an unelected and unaccountable commission is plainly repugnant to the Constitution’s vesting of that authority in the legislatures of the states,” he said.

But Seth Waxman, arguing for the Independent Redistricting Commission, urged the court to not take such a literal approach. He said when the U.S. Constitution refers to “the legislature” it means the legislative process of how laws are made.

In this case, the Arizona Constitution reserves the ultimate power to make laws to the people themselves. And here, the people delegated the power to draw the congressional lines to the commission.

Justice Antonin Scalia said there’s a flaw in that argument.

“At the time (the U.S. Constitution was written) there was no such thing as the referendum or the initiative,” he told Waxman.

“So when the dictionaries referred to ... ‘the power to make laws,’ it was always the legislature,” Scalia continued. “It was never the people at large because there was no such thing as the referendum.”

Lowenthal said HR 2501 is crafted in such a way that it is designed to survive even a high-court ruling that sides with the Arizona Republican legislative leaders. He pointed out that while the U.S. Constitution empowers legislatures to draw congressional lines it also permits Congress to “make or alter such regulations.”

He got Republican Dana Rohrabacher, also of California, as the other prime sponsor. It also has the support of Kirkpatrick and fellow Arizona Democrats Raúl Grijalva and Ruben Gallego, but none of Republican members of the state’s congressional delegation.

The fourth Democrat, Kyrsten Sinema, did not join as a sponsor, and did not return calls for comment.

Nothing in what the Supreme Court rules — or in HR 2501 — would have any effect on state legislative districts, as how they are crafted is not spelled out in the U.S. Constitution.

But there is a separate case pending before the nation’s high court on how those 30 districts were most recently crafted. That lawsuit, brought by Republican interests, challenges not the authority of the commission to draw the lines, but contends they were illegally drawn, creating unequal-size districts they contend were designed to favor Democrat candidates.

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