Justice Ruth Bader Ginsburg’s difficulty in carrying out her judicial duties has encouraged informal wagering about whether she can continue until President Trump leaves office. This is in bad taste and overshadows recognition of her outstanding career.

The problem of justices outliving their judicial capacity has recurred throughout U.S. history. But it may be growing more acute, as advances in health care enable physical strength to outlive mental capacity.

We do not yet have a satisfactory mechanism for addressing the issue. No statute forcing justices to leave office would be valid because the Constitution specifies that they “hold their Offices during good Behavior.” That’s a rough translation of the Anglo-Latin formula, “quam diu bene gesserit.” It literally means “so long has he shall have conducted himself well.” Justices serve until their death, retirement, resignation, or impeachment-and-conviction, whichever comes first.

One possible remedy is for family members or professional colleagues to pressure a failing justice into resigning or retiring. Another alternative is impeachment, conviction, and removal from office for “high … Misdemeanors.” In the constitutional context, this is a fiduciary standard, and is broad enough to include negligence or other breach of duty due to incapacity.

But neither pressure nor impeachment are satisfactory remedies. First, neither can be based fully on objective standards of competence. Is Justice Ginsburg better or less able to perform her duties than were Justices William O. Douglas or Hugo Black in their later years? Not only is that question often unanswerable objectively, but personal answers are likely to be colored by political preferences.

Similar political considerations may mar the decision of the justice himself. A jurist who might agree to being replaced by an Obama nominee might hang on to avoid being replaced by a Trump nominee — or vice versa. So there is no guarantee the object of pressure will yield to it.

The Constitution’s requirement that two thirds of senators vote to convict an impeached official offers some protection against arbitrary political action. But Congress has been unwilling to terminate distinguished judicial careers that way: The impeachment-and-conviction process has never been used successfully to remove a Supreme Court justice.

We are left with the alternative of constitutional amendment. But what kind of amendment?

One option is a fixed retirement age — perhaps 75 years, but this presents problems of its own. Some jurists are fading intellectually at 75, but others possess their full intellectual faculties, and can benefit the court with experience their younger colleagues lack. Moreover, as life expectancies change, the mandatory retirement age could become obsolete, necessitating further amendment.

There also are problems of fairness with a set retirement age: A justice appointed at age 45 is still relatively unseasoned but could enjoy 30 years of service. A justice appointed at 60 would serve only 15 years.

Perhaps worst of all, a fixed retirement age would further encourage presidents to pursue the irresponsible practice of nominating jurists as young as possible to make their presidential “legacies” endure as long as possible.

A better constitutional amendment would be one permitting each justice a single long term — for example, 16 years — without possibility of re-appointment.

This would ensure judicial independence. (The Constitution’s framers also considered a single long presidential term to ensure independence.) Yet if the term is not too lengthy, justices would face the prospect of eventually returning to private life — always a helpful perspective.

A single long term would ensure regular rotation on the court and reduce presidential incentives for nominating relatively untried people. For example, a president could select a more experienced 60-year old with some confidence that he or she would serve out his or her term. Single terms also would reduce the stakes inherent in any one appointment. Lower stakes could diminish the political furor now accompanying nominations.

Finally, a fixed term would correct a growing defect in the Constitution’s system of checks and balances. When the Constitution was adopted, life expectancy was much shorter than it is now. Justices appointed during the 1790s served an average of only 8-9 years before they died or resigned. When the court erred or overreached itself, the elected branches of government could respond through regular judicial replacements. Today, however, the average service on the court exceeds 20 years. Justice Anthony Kennedy continued his course of sometimes idiosyncratic decision making for more than 30 years.

Thus, a single term would restore the balance of legislative, executive, and judicial powers to one more consistent with the constitutional design.

Robert G. Natelson is a long-time constitutional scholar who has written extensively on federalism and on the Constitution’s meaning. He is senior fellow in Constitutional Jurisprudence at the nonprofit Independence Institute in Denver.