When the late U.S. Supreme Court Justice Thurgood Marshall went to Bethesda Naval Hospital with pneumonia in 1970, doctors told him that President Richard Nixon wanted to see his medical records.

Marshall gave consent, but with one addendum: Marshall scrawled “NOT YET!” on the folder that went to Nixon. Marshall did not retire until 23 years later.

Marshall's message was clear, and shared by most justices before and since: life-tenured Supreme Court justices don't like to be told when to retire or move on.

But presidents and others keep trying.

On May 10, Senate Judiciary Committee chairman Chuck Grassley, R-Iowa, said in a radio interview, “I just hope that if there is going to be a nominee, I hope it's now or within two or three weeks, because we've got to get this done before the election. So my message to any one of the nine Supreme Court justices, if you're thinking about quitting this year, do it yesterday.”

Grassley's unusual piece of advice has not yet been heeded. Given the unpredictability of justices' whims and health profiles, it could still conceivably happen. But it's not likely.

“Supreme Court justices make their own decisions about whether and when to step down from their posts,” former O'Melveny & Myers partner Ron Klain said in an interview. Klain is also a former Supreme Court law clerk, Judiciary Committee counsel, and White House official.

Klain added, “History is littered with examples of presidents, politicians, and pundits who tried to influence these decisions to no avail. I have no idea if any current members of the court intend to step down this year or the next, but I am absolutely certain that they will not be coaxed or cajoled into making a choice that is theirs alone to make.”

If anything, hinting that it is time to go seems to stiffen justices' resolve to stay.

Toward the end of the Obama administration, some academics urged Justice Ruth Bader Ginsburg to retire so she could be replaced by a like-minded liberal. Ginsburg dismissed the suggestion, asserting that the political climate at the time would have made it unlikely for a kindred nominee to be confirmed. To this day, Ginsburg insists she will stay on the job as long as she can perform her duties at “full steam.”

During his declining years, the late Chief Justice William Rehnquist was often asked about his health and retirement plans. His answer, which he acknowledged borrowing from schoolyard banter, was, “That's for me to know and you to find out.” He was still chief justice when he died of cancer in 2005.

The bipartisan urge to create Supreme Court vacancies runs strong among presidents who are mindful that filling the slots can be an important part of their legacies. In 1992, Bill Clinton paid a courtesy call to the court before he took office. Justice Harry Blackmun joked afterward that the eager president-elect was sizing up “us old goats” for coffins. Clinton got to appoint two justices: Ginsburg and Stephen Breyer.

Northern Illinois University political scientist Artemus Ward, author of a 2003 book about why justices leave the bench, said, “To think that the justices need retirement advice from the chair of the Senate Judiciary Committee, the president, or any other elected official is laughable.”

Ward continued: “Grassley is essentially urging one justice in particular—Anthony Kennedy—to retire now before the 2018 midterm elections to guarantee that a majority Republican Senate will be able to control the confirmation process and approve his replacement without any Democratic votes if necessary. Of course Kennedy already knows this and Grassley knows that Kennedy already knows this.” Kennedy has hired law clerks for next term, though that is not a definite predictor of his plans.

Ward points to at least one president in history who was a master at elbowing justices off the bench: Lyndon Johnson.

In 1965, Johnson persuaded Justice Arthur Goldberg to step down after only three years on the court to become U.S. ambassador to the United Nations. In 1967, Johnson appointed Ramsey Clark as attorney general, which compelled Ramsey's father, Justice Tom Clark, to leave the bench to avoid conflicts of interest. Abe Fortas succeeded Goldberg, and Marshall succeeded Clark.

“Of course the chair of the Senate Judiciary Committee does not possess the kind of powers a president does when it comes to inducing departures,” Ward said. “That is why Grassley has resorted to one of the few tools at his disposal: public pressure.”