The U.S. Constitution is the supreme law of the land. In theory, it acts as one unifying body of law for each and every corner of that land. But in practice, the Constitution can mean different things in different places. That’s because federal law divides the United States into 12 geographic districts, each with its own separate federal court of appeals, whose constitutional interpretations apply only within its own circuit.

And now, Arizona wants to switch circuits. Governor Doug Ducey, Senator Jeff Flake, and Representative Matt Salmon announced a joint effort last week to sever their state from the Ninth Circuit Court of Appeals, citing its heavy workload, high rate of reversal, and slow resolution of cases.

Which states are placed in which federal appellate circuits might seem a little wonky, but the practical implications are huge. Except for the few petitions granted by the Supreme Court each year, the circuit courts of appeal are the final arbiter of almost all federal cases.

And Arizona’s leaders have a point. If you designed the American federal judiciary from scratch today, the Ninth Circuit probably wouldn’t exist. Of the 13 circuit courts of appeal, it’s by far the largest, spanning the states of Alaska, Arizona, California, Idaho, Montana, Nevada, Oregon, and Washington, as well as the Pacific territories of Guam and the Northern Mariana Islands. When Congress created the court in 1891, its vast territory was sparsely inhabited, holding less than 4 percent of the U.S. population. Now, after 125 years of westward migration, more than 20 percent of all Americans live within its jurisdiction.

With great size comes great logistical challenges. “The Ninth Circuit is by far the most overturned and overburdened court in the country, with a 77 percent reversal rate,” Ducey said in a statement last week. “Meanwhile, due to its voluminous caseload and disproportionate size, the Ninth Circuit has an abysmal turnaround time of over 15 months for an average ruling—a figure that’s only going to grow as the docket does.”

In a letter to Speaker of the House Paul Ryan and Senator Majority Leader Mitch McConnell last October, Ducey offered two possible solutions. First, he proposed that Arizona could be moved into the neighboring Tenth Circuit, which currently stretches from New Mexico to Wyoming.

Alternatively, he suggested that Congress spin off Arizona and “other noncoastal states” into a new Twelfth Circuit, which would logically also include Idaho, Montana, and Nevada. The shrunken Ninth Circuit would then consist of Alaska, California, Hawaii, Oregon, and Washington, as well as the Pacific territories.

Splitting the circuit, however, isn’t that easy. Much of the difficulty can be traced to California’s disproportionate influence. The Golden State possesses half of the Ninth Circuit’s population, and none of its neighbors even come close. Cases from the state fill the court’s dockets, most of its judges and staff live and work there, and most of its hearings take place in San Francisco or Pasadena. (The only other city where it holds year-round hearings is Seattle; the court also convenes a smaller number of panels in Alaska and Montana each year.)

And like moons caught in Jupiter’s orbit, California’s neighbors are hindered in their attempt to escape by its mass. If a new circuit court gets California and only one or two other states, the Golden State could overwhelm its docket and its character. If, on the other hand, too many states join California in a new circuit, the court could again become too large to manage.

Proposed splits have received ample study over the last three decades, most recently in 1998, when Congress appointed a commission headed by retired Justice Byron White to reexamine the federal appeals courts’ structure. Central to the commission’s purpose was assessing the viability of splitting the Ninth Circuit. In the end, the commission recommended against it. Instead, it proposed three administrate divisions within the circuit to alleviate logistical burdens while maintaining court cohesion.

“Any realignment of circuits would deprive the West Coast of a mechanism for obtaining a consistent body of federal appellate law, and of the practical advantages of the Ninth Circuit administrative structure,” the commission concluded. “Moreover, it is impossible to create from the current Ninth Circuit two or more circuits that would result in both an acceptable and equitable number of appeals per judge and courts of appeals small enough to operate with the sort of collegiality we envision, unless the State of California were to be split between judicial circuits—an option we believe to be undesirable.”

Splitting the state between two circuits would alleviate the broader problem, the commission reasoned, but at the cost of legal chaos in California itself. No state currently obeys the rulings of two different federal appellate courts, and such an arrangement would invite constant Supreme Court intervention to harmonize their rulings, thereby defeating the purpose of the courts. The commission also rejected the idea of placing California in its own circuit, which would deprive the court of its federal character and give disproportionate influence to a single state's senators when selecting potential judges.

The commission’s aversion to splitting the Ninth Circuit wasn’t shared by the Supreme Court justices at the time, including Justices Sandra Day O’Connor and John Paul Stevens. Justices Anthony Kennedy and Antonin Scalia even proposed a three-circuit split to the commission, with northern California, Hawaii, and Nevada in one circuit, southern California, Arizona and the Pacific territories in a second circuit, and Idaho, Montana, Oregon, and Washington in a third circuit. The commission, however, emphatically rejected the idea of splitting California between two federal circuits.

Carving up large circuits into more manageable ones isn’t completely unprecedented, though. In 1929, Congress split the Eighth Circuit and reorganized the Rocky Mountain states and some of the Great Plains states into the Tenth Circuit. But some historical proposals also had less-than-noble motives. During the 1960s, the Fifth Circuit, which encompassed Texas, Florida, and the Deep South, was among the largest and most overburdened appellate courts in the country. It also had a relatively progressive bench and acted as a bulwark of anti-segregation rulings in the South.

In 1964, Southern legislators proposed a bill that would have split the Fifth Circuit along the Mississippi River into two smaller circuits. The existing judges would be divided between them and new judges would be appointed to fill each bench. Since senators can effectively block judicial nominations through the custom of senatorial courtesy, Southern senators could have exercised significant influence over the new appointments. Civil-rights activists rallied and the plot against the Fifth Circuit failed, but Congress eventually did split the Eleventh Circuit off from it in 1981—out of, as a New York Times editorial noted, “not racism but practicality.”

Arizona obviously isn’t a Jim Crow state, and Ducey and his colleagues aren’t segregationists. But the Ninth Circuit's liberal reputation, deserved or not, frequently hangs over the discussions of its fate. In 1990, Washington Senator Slate Gorton tried to move the Pacific Northwest into its own circuit; critics, including Chief Judge Alfred Goodwin, linked the effort to recent pro-environmental rulings. In 1997, Alaska Senator Ted Stevens led a failed legislative revolt to carve all of the states except California and Nevada into a new Twelfth Circuit after a three-judge panel with no Alaska-based judges ruled on a major Alaska Native case.

Arizona has also suffered a number of major legal defeats at the Ninth Circuit in recent years. The court ruled against the state’s controversial SB1070 immigration law and a policy that denied driver’s licenses to people who entered the country illegally as children, a ban on health benefits for same-sex partners of state employees, a 20-week ban on abortions and tougher restrictions on abortion medications, an anti-day-laborer law, and a ban on pro-life licenses plates, to name a few.

None of the officials who backed splitting the Ninth Circuit last week mentioned these rulings, but the state's continuous record of defeat couldn’t have been far from their minds. Nor are similar complaints far from the Supreme Court justices’ minds. Justice Kennedy, who served on the Ninth Circuit prior to his current job, warned against manipulating the circuit courts for ideological reasons during a House Appropriations Committee hearing in 2007.

“You don’t design a circuit around the perceived political leanings of the judges,” he told the committee. “That’s quite wrong. You design it for other, neutral reasons.” Justice Clarence Thomas, who also testified before the committee, echoed those sentiments.

At the same time, Kennedy also cited “sound structural reasons” why the Ninth Circuit should be split. Because of its size, a three-judge panel consisting of “a circuit judge, a senior judge, and a visiting judge from another circuit or a district court can bind 22 percent of the nation’s population,” he noted. The 29-judge bench is too large and too dispersed to maintain collegiality, Kennedy argued, and having an “amorphous, remote, distant court” makes it hard for the public, the press, and bar associations to be familiar with the judges who serve on it.

There’s no straightforward solution to these confounding problems. In that respect, the debate echoes one that has raged in the United Kingdom, known as the West Lothian question. Why, the question asks, do Scottish Members of Parliament get to vote in Parliament on English laws when English MPs have no voice in Scottish laws passed in the Scottish Assembly?

Thousands of studies and white papers can be found on the question and its possible resolution, but one of the most memorable assessments comes from former Lord Chancellor Darry Irvine. “The best answer to the West Lothian question,” he told the House of Lords during a 1999 debate, “is to stop asking it.”