Despite “serious risks to national security,” the special counsel investigating President Biden’s handling of classified documents, Robert Hur, isn’t bringing charges. His reasoning — the president’s advanced age — has the White House angry, opponents salivating, and America at risk.

“At trial,” Mr. Hur wrote in his report to Attorney General Garland, “Mr. Biden would likely present himself to a jury, as he did during our interview of him, as a sympathetic, well-meaning, elderly man with a poor memory.”

Mr. Biden’s “memory was significantly limited,” Mr. Hur wrote, in recorded interviews with his ghostwriter, Mark Zwonitzer, in 2017. He was “often painfully slow … struggling to remember events and straining at times to read and relay his own notebook entries.”

Mr. Hur said Mr. Biden’s memory “was worse” last year. He “did not remember … when his son Beau died, and his memory appeared hazy” on Afghanistan. “Among other things, he mistakenly said he ‘had a real difference’ of opinion” with an ally whom he’d “cited approvingly” in a memo.

On Thursday, Mr. Biden said, “My memory is fine.” He recalled thinking, “How in the hell dare he raise” Beau’s death, before crediting the rosary beads he has carried in his honor to “Our Lady of,” and taking a long pause without producing the name. His attorneys wrote to Mr. Hur that his characterizations were not “accurate or appropriate.” The report’s “highly prejudicial language,” they said, described “a commonplace occurrence among witnesses: a lack of recall of years-old events.”

Expect Mr. Biden’s lapses to be compared to, say, President Reagan, who was pilloried by Democrats for responding, “I do not recall” or “I can’t remember” 88 times in his post-presidential testimony about the Iran-Contra affair years earlier.

Reagan stressed that he averaged 80 meetings a day and generated 50 million documents during eight years in office. Those mundane activities couldn’t be considered “flashbulb moments” like the loss of a child, nor did Reagan ask anything like, as Mr. Biden did, “When did I stop being vice president?” 

Mr. Hur’s report comes as Democrats struggle to squelch concerns about Mr. Biden’s faculties. In August, an AP-NORC poll found that 77 percent of Americans — including 69 percent of Democrats — judged him too old to be an effective president.

From President Arthur’s terminal kidney disease to President Cleveland’s cancer surgery and President Wilson’s debilitating stroke, the people’s right to know has often been infringed. In the wake of the special counsel’s report, some Republicans in Congress urged the Cabinet to invoke the 25th Amendment. 

Passed in 1967 to deal with a situation like Wilson’s, it allows for a president’s removal. The best prescription for the nation is to make any such move from a place of sincere, bipartisan concern, not out of malice.

It doesn’t help silence worries that Mr. Biden keeps out of sight. In his first two years, he granted the fewest interviews since Mr. Reagan, who lost time recovering from an assassination attempt, and he held the third fewest news conferences of any president in 100 years. He’s also skipping the traditional interview at the Super Bowl this weekend.

Mr. Biden has declined to take a cognitive test as President Trump did to fend off similar criticism, leaving the public guessing. A recent commercial by the Lincoln Project sought to portray Mr. Trump as “senile,” but Mr. Hur just made that counter-spin more difficult.

Confirmation bias ensures that Mr. Biden’s every lapse will now buttress the impression of infirmity, but in the ravages of age, the public will see their own mortality. They’ll be reminded of elders who have drifted into the twilight of confusion and sympathize with the president.

Mr. Biden’s 1972 run for the Senate, when he was 29, navigated the issue with aplomb. He instructed his campaign to attack the sharpness of the 63-year-old incumbent, Senator Boggs. Wary of appearing cruel to older voters, though, he kept calling his opponent a “helluva nice guy.”

The details in the special counsel’s report, and Mr. Biden’s public struggles, raise stakes far more serious than November’s election. Perception may matter in campaigns, but with enemies circling on the world stage and trouble at home, America can’t afford to be guessing about the reality of a president’s health.