Is there a precedent for a POTUS to do so?
Doesn't seem so.
>> Four out of the past seven funerals for a Supreme Court justice have either had the president or vice president in attendance.
Former President George W. Bush attended the funeral for Chief Justice William Rehnquist.
Former President Bill Clinton attended the funerals for former Chief Justice Warren E. Burger and Justice William Brennan but did not attend the funerals for Justices Harry Blackmun or Lewis F. Powell Jr.
Former Vice President Al Gore attended the funeral for Justice Thurgood Marshall. << ---
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