Special Counsel Jack Smith’s hour-long public interview at London would appear to mark the prosecutor’s transformation into a political pundit. The colloquy with MSNBC’s Andrew Weissmann — formerly Special Counsel Robert Mueller’s top deputy — followed a keynote lecture last month at George Mason University. Foiled in his efforts to convict President Trump, Mr. Smith now feels ready to let loose in the court of public opinion.

Mr. Smith’s newfound volubility strikes us as a baleful development for a country where prosecutions are increasingly seen as political. The dismissals of Mr. Smith’s Mar-a-Lago and January 6 cases mean that Mr. Trump’s presumption of innocence is intact in both. That is why it struck us as wrongheaded for Attorney General Merrick Garland to release Mr. Smith’s final report, where he claimed that a conviction was foreordained if Vice President Harris won in 2024.

Mr. Smith wrote that “the admissible evidence was sufficient to obtain and sustain a conviction.” That judgment, though, was never confirmed by a jury — solely to whom the Constitution assigns the ultimate weighing of evidence — or even put before one. Now more commentary could be coming as the Times reckons that “Mr. Smith has ended his self-imposed silence since resigning from his position days before Mr. Trump returned to office.”

In his speech last month the special prosecutor ventured that “What I see happening at the Department of Justice today saddens me and angers me — selfless public servants fired for doing their job, the government using the vast powers of the criminal justice system to target citizens for exercising their constitutional rights.” Mr. Smith told Mr. Weissman that “the idea that politics played a role in who worked on that case, or who got chosen, is ludicrous.”

We get that the Trump Administration’s campaign against Mr. Smith has been unrelenting. Nearly every Department of Justice staffer seconded to the special counsel’s squad has been fired, and now Mr. Smith himself is facing what appear to be far-fetched allegations that he violated the Hatch Act. That law banning political activities by federal employees has never, though, been applied to a prosecutor.

Special counsels, though, are appointed for a specific task, and their remit expires when that assignment is complete. Prosecutors work best when they speak in the courtroom and are taciturn outside of it. The same goes for, say, New York’s attorney general, Letitia James, who ran for office in 2018 vowing to “shine a bright light” into Mr. Trump’s business dealings. That too, appeared to us to be political and injurious to the presumption of innocence.

Mr. Smith on Wednesday appeared in a video crafted by a group, Justice Connection, that advocates on behalf of fired DOJ employees. His participation is a boon for those who resent Mr. Trump’s leadership of the DOJ. The American people, though, knew all about Mr. Smith’s cases when they went to the polls in 2024. Their verdict made the 45th president the 47th one — and ended Mr. Smith’s quest before he could make opening arguments.