Attorney General Merrick B. Garland on Thursday released the report by Robert K. Hur, the special counsel Mr. Garland had assigned to investigate how classified documents ended up in an office formerly used by President Biden and in his home in Delaware. Here are some takeaways.

Mr. Hur was bound by a Justice Department policy that holds that the Constitution implicitly makes sitting presidents temporarily immune from prosecution, so he could not have charged Mr. Biden even if he wanted to. But Mr. Hur wrote that Mr. Biden should not be charged regardless.

“We conclude that no criminal charges are warranted in this matter,” he wrote. “We would reach the same conclusion even if Department of Justice policy did not foreclose criminal charges against a sitting president.”

Mr. Hur wrote that he had found evidence that Mr. Biden had willfully retained and disclosed sensitive information after he left the vice presidency in 2017. But he said the evidence fell short of what would be necessary to “establish Mr. Biden’s guilt beyond a reasonable doubt.”

Mr. Hur listed various reasons that a jury might reasonably doubt that Mr. Biden had “willfully” retained classified documents after leaving the Obama White House, including that Mr. Biden had reported the problem and invited investigators to search his home. But Mr. Hur cited another reason with potentially explosive political implications for the 81-year-old president as he seeks re-election: that he had memory problems.

Mr. Hur wrote that Mr. Biden’s memory “appeared to have significant limitations.” The special counsel portrayed Mr. Biden’s recorded conversations with his ghostwriter in 2017 as “often painfully slow, with Mr. Biden struggling to remember events.” And, the report said, his recollection “was worse” in his interview with Mr. Hur in October, when Mr. Biden came off, he said, “as a sympathetic, well-meaning, elderly man with a poor memory.”