The standard reasons for investigative secrecy apply with much less force here. One of those reasons is that the department does not want to tip people off to the existence of an investigation, which might allow them to hide evidence, coordinate cover stories or flee the country. But these matters, to varying degrees, have already been publicly aired, discussed and reported on.

Some lawyers have also suggested to me in recent days that the public will get greater insight into the department’s work investigating Mr. Trump if (or perhaps when) prosecutors start filing charges that more directly implicate him. But it is possible that in some areas, the federal government will never charge anyone, perhaps because it considers the matter closed or because it opted to cede the investigation to a local prosecutor. If that is what happened, the public deserves to know in order to assess both the performance of the Justice Department and the extent to which federal law enforcement officials have reviewed Mr. Trump’s conduct.

Furthermore, the department’s fully ceding ground here could create a void easily filled with inaccurate information and politically motivated speculation. About the Mueller investigation and impeachment proceedings, Mr. Trump made deeply misleading public comments on social media, in public appearances and in interviews, and allies and surrogates echoed his dubious claims and cast him as a political martyr suffering at the hands of crazed opponents. The claims were often tenuous or transparently false, but they were effective in persuading a significant bloc of Americans to discount the findings of the investigations.