Kermit Roosevelt is a constitutional scholar and professor at the University of Pennsylvania Law School. Ruth-Helen Vassilas, a Penn Law grad, is an associate in the London office of Skadden, Arps, Slate, Meagher & Flom LLP. The opinions expressed in this commentary are those of the authors; view more opinion articles on CNN.

(CNN) While on his recent book tour, Supreme Court Justice Neil Gorsuch said that the framers of our Constitution did not want "nine old people in Washington sitting in robes telling everybody else how to live." Yet that is the current reality of our Supreme Court.

These days, it's the justices, and not the people or their elected representatives, who decide who gets health care and who can vote, whom we can marry and who's allowed into the country, who's won a presidential election and who can spend money on the next one.

Meanwhile, the court has also had a historic lack of turnover and nationally embarrassing confirmation hearings. Justices often serve past their prime, including one who stayed after a debilitating stroke , until they feel assured that a politically like-minded president will occupy the Oval Office and guarantee an appropriate replacement. When unexpected vacancies occur, partisans on both sides wage no-holds-barred battles for the seat.

These trends make it no wonder that three-fourths of the country supports swapping out Supreme Court life tenure for term limits. Judicial term limits are not a novel concept; they already exist for many of the highest courts across the Western world. Plus, 49 of 50 US state courts of last resort have term limits, retention elections, or mandatory retirement age.

Even some justices support term limits. Chief Justice John Roberts, while working in the White House Counsel's office in 1983, wrote that "there is much to be said for changing life tenure to a term of years, without possibility of reappointment...." He recognized that "a judge insulated from the normal currents of life for 25 or 30 years was a rarity then, but is becoming commonplace today."

The most direct way to adopt term limits would be through a new constitutional provision. The Constitution, however, is notoriously difficult to amend. Obtaining both House and Senate supermajority support, followed by ratification from 38 state legislatures, would be nearly impossible. But there are other ways to achieve term limits.

Some suggest encouraging court nominees to pledge to retire after a fixed term. Former White House Counsel Robert Bauer, for instance, wrote an essay ahead of Chief Justice Roberts' 2005 confirmation asking that Roberts pledge to serve a fixed term if confirmed. Such an assurance, however, would be unenforceable. A justice, at the conclusion of the promised term, could easily contend that the national importance of his or her continued service outweighs words uttered under pressure long ago. Congress could, in theory, impeach a justice who refused to adhere to the pledge. Nevertheless, removal requires two-thirds Senate approval and could fall prey to the same partisan dysfunction as the confirmation process.

Others suggest imposing a mandatory retirement age instead of term limits. This approach, though, would be discriminatory and ineffective. It would increase the incentive to nominate young judges rather than the best available legal minds and would fail to regularize the appointment process.

The best solution is to create Supreme Court term limits by statute. Several proposals exist for statutory term limits. The one we favor would give justices a fixed term of 18 years. Appointments would be staggered to allow each president two appointments per term, one in both the first and third year.

As each new justice joins the bench, the most senior justice would move to senior status. Justices with senior status would retain the option to sit on lower courts, as Justices Sandra Day O'Connor and David Souter have done post-retirement, and to serve as an active justice as needed, as Justice John Paul Stevens proposed in 2010. The lengthy fixed term would preserve judicial independence, while the regularized appointment process would make the court more responsive to the outcomes of national elections and less subject to chance and partisan hardball.

There's a question of what would happen to the current justices. Some scholars suggest applying the statutory timeframe to them retroactively so that, following a president's first appointment, the most senior sitting justice would be required to move to senior status. Because the sitting justices took office under a different set of expectations, however, such removals strike us as extreme.

Fortunately, they are not necessary. The more moderate solution would be to permit the current nine to keep their seats indefinitely. Though that may mean a 10 or 11-member court for a time, this temporary outcome is preferable to waiting in vain for the "perfect" moment to implement term limits. Each passing year under the current regime increases the likelihood of disruptive vacancies and strategic retirements.

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This proposal is lawful under the Constitution. First, Congress has the authority to change the size of the court and has done so repeatedly throughout history. Second, federal judges are constitutionally entitled to "hold their offices" during good behavior and not have their salaries reduced. This plan does not diminish salaries, and it is consistent with a current US law (28 US Code § 371(b)) that states explicitly that district and circuit judges who take senior status "retain the office." It follows that our legislators can assign senior status to justices, as well.

Political clashes, coupled with Methuselahn tenures, have eroded the institutional integrity of the Supreme Court. By statutorily setting term limits, we can bring predictability and fairness to a broken appointment process. Moreover, we will reduce partisan conflict and appropriately limit the influence of the "nine old people in Washington."