A failure to indict Mr. Trump in these circumstances would imply that a president — who cannot be indicted while in office — is literally above the law, in defiance of the very notion of constitutional government. It would encourage lawlessness by future presidents, none more so than Mr. Trump should he win the next election. By contrast, the rule of law would be vindicated by a Trump conviction. And it might be enhanced by a full judicial airing of Mr. Trump’s possible crimes in office, even if it ultimately fails.

And yet Mr. Garland cannot be sanguine that a Trump prosecution would promote national reconciliation or enhance confidence in American justice. Indicting a past and possible future political adversary of the current president would be a cataclysmic event from which the nation would not soon recover. It would be seen by many as politicized retribution. The prosecution would take many years to conclude; would last through, and deeply impact, the next election; and would leave Mr. Trump’s ultimate fate to the next administration, which could be headed by Mr. Trump.

Along the way, the prosecution would further enflame our already-blazing partisan acrimony; consume the rest of Mr. Biden’s term; embolden, and possibly politically enhance, Mr. Trump; and threaten to set off tit-for-tat recriminations across presidential administrations. The prosecution thus might jeopardize Mr. Garland’s cherished aim to restore norms of Justice Department “independence and integrity” even if he prosecutes Mr. Trump in the service of those norms. And if the prosecution fails, many will conclude that the country and the rule of law suffered tremendous pain for naught.