The op-ed said this stems from a long standing rule in Anglo-American common-law; a person, “cannot [act] as a court and a litigant in the same case.”
“The Justice Department was right that guidance could be found in the enduring principles that no one can be both the judge and the defendant in the same matter, and that no one is above the law.
The Constitution specifically bars the president from using the pardon power to prevent his own impeachment and removal. It adds that any official removed through impeachment remains fully subject to criminal prosecution. That provision would make no sense if the president could pardon himself.
The Constitution’s pardon clause has its origins in the royal pardon granted by a sovereign to one of his or her subjects. We are aware of no precedent for a sovereign pardoning himself, then abdicating or being deposed but being immune from criminal process. If that were the rule, many a deposed king would have been spared instead of going to the chopping block.”
\**The authors of the op-ed were Harvard constitutional law Professor Lawrence Tribe, Richard Painter, former chief ethics lawyer for President George W. Bush, and Norm Eisen, former chief ethics lawyer for President Barack Obama.*