The indictments on Monday of the former Trump campaign officials Paul Manafort and Rick Gates have some prominent conservatives openly considering desperate measures. The Wall Street Journal editorial board called on the special counsel whose investigation led to the indictments, Robert Mueller, to resign, arguing that he lacks the “critical distance” to carry out the inquiry. So did the New York Post columnist Michael Goodwin.

But the most radical suggestion came from two former Republican administration lawyers. To forestall a deepening crisis that could cripple the Trump White House, these lawyers, David B. Rivkin Jr. and Lee A. Casey, urged the president to issue a blanket pardon to anyone involved with Russian efforts to influence the 2016 presidential election. This isn’t just a fringe possibility. A reporter raised the idea on Tuesday; Mr. Trump didn’t answer the question.

Though such a move would not violate the Constitution, it would provoke a political disaster.

President Trump has tweeted that he has the “complete power to pardon.” As someone who supported the broadest reading of executive power as a deputy assistant attorney general during the George W. Bush administration, I think that Mr. Trump has the Constitution about right. Article II declares that the president “shall have power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.” President Trump can clearly pardon anyone — even himself — subject to the Mueller investigation.

But unless Mr. Trump wants to meet the same end as Richard Nixon, he should resort only to pardons that promote the central purpose of the power. As Alexander Hamilton explained in Federalist 74, the Constitution creates a pardon power out of “humanity and good policy” to allow for “mitigation from the rigor of the law.”