Imagine that a federal prosecutor had gone after The Washington Post Company back in the 1990s on the theory that the reluctance of its magazine, Newsweek, to publish an article about a sex scandal involving Bill Clinton constituted an illegal campaign contribution to the Clinton campaign.

The ensuing outcry and fear that prosecutors would begin substituting their own news judgment for that of editors wouldn’t have been limited to First Amendment absolutists like Nat Hentoff. It would almost certainly have been widely shared. And justifiably so.

As Newsweek itself eventually found out via Matt Drudge, and as the framers of the First Amendment well understood, free-market competition is better regulation of press behavior than any second-guessing by government lawyers threatening criminal prosecution based on creative theories of campaign finance law.

If the National Enquirer’s failure to publish an article about Donald Trump amounts to an undisclosed campaign contribution to the Trump campaign, how much did the New York Times contribute to the Trump campaign with the articles it actually did publish about Hillary Clinton’s private email server?

Maybe every news organization should be required to employ a team of campaign finance lawyers, evaluating every article, photograph, and unpublished story idea for its impact on the campaign’s outcome, assigning each a dollar value, and totaling it all up and reporting it to the Federal Election Commission and the U.S. attorney every three months.

President Trump’s rhetoric — “failing New York Times,” “enemy of the people” — generated, earlier this year, an unusual coordinated self-congratulatory editorial campaign in defense of press freedom. Yet now federal prosecutors in New York are happily announcing the imposition of “remedial measures” and “annual training” with “required attendance” for a media company — and not a peep of protest has been heard from the Freedom Forum, the professors of journalism, the Committee to Protect Journalists, or the rest of the industry whose level of self-regard was recently demonstrated by Time’s decision to make journalists their persons of the year.

It will be protested that Enquirer parent American Media Inc. isn’t a journalism company but an entertainment company, or that decisions not to publish are somehow different than decisions to publish, or that because actual money changed hands, this somehow doesn’t amount to real journalism.

Yet First Amendment law has advanced in America on the basis of sketchy outlets such as Benjamin Bache’s Philadelphia Aurora and Jay Near’s Saturday Press. Near v. Minnesota was the precedent for the Supreme Court’s decision allowing the New York Times to go ahead and publish the Pentagon Papers.

Even “respectable” press companies routinely hire sources as “consultants” or on-air contributors, pay them for photos, or fly them to New York and put them up in fancy hotels. If a German book publisher pays James Comey a million dollar advance for a negative tale about President Trump, is that a campaign contribution to Congressional Democrats?

The AMI “non-prosecution agreement” is just one piece of the bigger story of President Trump’s own Justice Department trying to undermine the presidency itself. This is a campaign that also involves targeting Trump’s first national security adviser, Michael Flynn, with a perjury trap along the lines of which none other than Justice Ruth Bader Ginsburg herself has warned.

President Trump, on Twitter, has been describing all this as the “Russian Witch Hunt Hoax,” declaring, “Jeff Sessions should be ashamed of himself for allowing this total HOAX to get started in the first place!”

Mr. Sessions, the former attorney general on whose recused watch was appointed Special Counsel Robert Mueller, is a convenient scapegoat. The Justice Department, however, is part of the executive branch headed by President Trump, and under the constitution’s Article II, Messrs. Sessions and Mueller are “inferior officers.”

If Mr. Trump allows Mr. Mueller and former Deutsche Bank lawyer Robert Khuzami, now acting U.S. attorney in Manhattan, to mire his presidency in legal quicksand, he’ll bear some of the blame himself. It’s Mr. Trump’s Justice Department, Mr. Trump’s prosecutors, Mr. Trump’s executive branch that is pursuing this case.

Perhaps if Mr. Trump moves to shut the whole thing down it will trigger outrage from Congress or the public about interfering into an ongoing criminal investigation into foreign interference with an American election. My own sense, though, is that the American people would be receptive to an argument that if you want to defeat a president, you need to do it by running against him in an election rather than by pushing the prosecutorial envelope with perjury traps and novel interpretations of campaign finance law.

If Mr. Trump can make that case, it’d be a win not just for his own presidency but for the office itself. Future occupants of the office, Democrat or Republican, would be grateful, as would be citizens whose security depends on a president able to focus on the job with a boldness un-sapped by prosecutorial excess.