Crucial information about the causes of the looming political battle over the Supreme Court, can be found — of all places — in the May-June 2017 issue of Contingencies, the official publication of the American Academy of Actuaries.

In an article provocatively titled “The Supreme Court has a Longevity Problem,” David Fishbaum of the management consulting firm Oliver Wyman explained how a social achievement that the Founders never imagined is destabilizing their constitutional design: average life expectancy has increased from roughly 40 years in the late 18th century to almost 79 years today.

Gone are the days when anyone considers the federal judiciary the “least dangerous” branch, in Alexander Hamilton’s famous phrase.

The Supreme Court may have “no influence over either the sword or the purse,” as Hamilton wrote, but by aggressively reviewing the constitutionality of state and federal statutes and executive actions, the court has evolved into a kind of super-legislature whose rulings determine the rights and livelihoods of millions.

And when some of that power may be transferred to a 49-year-old man with, on average, 33 years ahead of him — as occurred with President Trump’s appointment of Neil M. Gorsuch in 2017 — the constitutional guarantee of judicial life tenure begins to look less like insulation against political pressure and more like a way to enshrine the preferences of a transitory presidential administration and Senate majority for decades.

“The trend of living longer can be expected to significantly reduce the number of appointments over the next 100 years, extend the average tenure, and potentially upset the balance of power among the three branches,” Fishbaum wrote.

Using standard statistical methods and assumptions, he estimated that there will be only 25 new Supreme Court appointments over the next century, compared with 47 in the previous 100 years and 60 between 1869 and 1969. Meanwhile, average time on the bench could rise to 35 years, nearly double what it was (18.1 years) in the century between World War I and the Trump administration. Only one president in the last century — one-termer Jimmy Carter — made no Supreme Court appointments. Over the next century there is a 1 in 10 chance that a two-term president will make none, according to Fishbaum.

“The lack of movement on the court will amplify the significance of every appointment moving forward and is likely to make the appointment process even more vitriolic, given what is at stake,” Fishbaum predicted, accurately.

Because of Senate Majority Leader Mitch McConnell’s (R-Ky.) manipulation of the confirmation process to shut out President Barack Obama’s Supreme Court choice in 2016 and Trump’s improbable victory that year, Democrats find themselves on the wrong side of the actuarial charts. In the wake of 87-year-old Justice Ruth Bader Ginsburg’s death, they could face near-permanent minority status at the Supreme Court.

The response some Democrats advocate — increasing the nine-member court’s legally authorized size and packing it with liberals — might avenge 2016 and resolve their short-term policy concerns while plunging the court, and the country, into even deeper division and crisis.

What the country needs — badly — is to lower the stakes attached to personnel changes at the Supreme Court and the lower courts. Since limiting or abolishing judicial review might not be desirable even if it were possible, the best alternative is to end life tenure for federal judges in favor of a specific term limit or a mandatory retirement age.

Whether this must be done by amending the Constitution or whether a change in federal law could suffice is just one of many challenging questions such a proposal would face.

And that’s before you get into the really fine points. Fishbaum modeled a plan whereby eight current justices, plus a new appointee, received fresh terms, limited to 18 years each. This nearly doubled predicted turnover for the next century from 25 to 49. But it accomplished that at the cost of creating a 41 percent chance that a single two-term president could appoint a court majority.

A different plan, in which seats would come open on a staggered basis every four years, and incumbent justices could be eligible for reappointment, eliminated most of that risk. That design, however, allowed somewhat fewer new appointments over 100 years.

Whatever its precise features, the crucial advantage of term limits or mandatory retirement is to reduce the discretion members of the court have over how long they serve, and the accompanying incentive to “time” retirement for ideological or partisan advantage, which is unseemly — and, often, futile.

An impartial rule that applied equally to all would lower political tensions and cross a major item off each individual jurist’s worry list.

The Founders did not design the U.S. political system for a world in which vigorous old age is the norm. We should update it, urgently.

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