President Trump could yet wield a potent law in his defense against charges related to the documents seized at Mar-a-Lago — the Constitution’s First Amendment. That favored protection of the press could prove to be the former commander-in-chief’s best defense. 

Prosecutors, now working with a special counsel, John “Jack” Smith, appear close to seeking an indictment of Mr. Trump under the Espionage Act of 1917. That statute has already played a central role in the government’s argument for a search warrant and is likely to be at the center of the government’s criminal case. 

The Espionage Act criminalizes the handling of materials “relating to the national defense.” Those materials need to be “closely held” and their disclosure “potentially damaging to the United States” or “useful to an enemy of the United States.”

While the Espionage Act has been on the books for more than a century, it has been dogged by constitutional challenges ever since President Wilson in 1915 called for legislation that would punish those who “poured the poison of disloyalty into the very arteries of our national life.” Wilson sought to punish not just leaks, but dissent. 

That intention came into focus in 1918 with an amendment known as the Sedition Act, appended to the Espionage Act when the latter was just a year old. The Sedition Act made it a crime to “willfully utter, print, write, or publish any disloyal, profane, scurrilous, or abusive language” about America’s government or Constitution.

The 1919 case of Schenck v. United States saw a unanimous Supreme Court uphold the Sedition Act, ruling that the First Amendment did not protect pacifist activists who circulated during wartime literature against the draft. Justice Oliver Wendell Holmes, in his opinion for the court, articulated the “clear and present danger” standard. In other words, one can’t yell “fire” in a crowded theater. 

In another case from the same year, Abrams v. United States, the court upheld the conviction of “rebels, revolutionists, and anarchists” for distributing “copies of a leaflet or circular, printed in the English language, and of another printed in the Yiddish language” that denounced America’s entry into World War I and called for domestic revolution.

The court upheld the conviction, but Justice Holmes dissented, applying his own standard to arrive at the conclusion that “Congress certainly cannot forbid all effort to change the mind of the country. Now nobody can suppose that the surreptitious publishing of a silly leaflet by an unknown man, without more, would present any immediate danger.” 

The Sedition Act was repealed in 1921, but the Espionage Act found itself back in court two decades later, in Gorin v. United States. While the justices affirmed a conviction of a Soviet spy, the opinion by Justice Stanley Reed considered the argument that the “national defense” standard was fatally vague. What that included was, the justices ruled, a question for the jury. 

In 1971, in New York Times Co. v. United States, Attorney General Mitchell tried to use the Espionage Act to block the Gray Lady. In a 6-to-3 holding, the Nine ruled that this expansive reading was at odds with the First Amendment and noted that the drafters of the Espionage Act were unwilling to clothe the president with such far-reaching powers to monitor the press. 

Prosecutors looking to cudgel Mr. Trump with the Espionage Act will likely cite the prosecutions of Private Chelsea Manning and the consultant Edward Snowden, both of which involved the statute now being turned against the former president. Manning’s sentence was commuted by President Obama, and Mr. Snowden is a fugitive in Russia, where he was granted citizenship by President Putin. 

Yet another target of Espionage Act prosecution has been the founder of WikiLeaks, Julian Assange. Mr. Assange was indicted in 2019 on 17 counts of violating the law for leaking hundreds of thousands of Department of State cables, many of which were published by the New York Times despite discouragement from Washington. Mr. Assange is in England, fighting extradition to America. 

In a joint open letter penned by the Times, the Guardian — another paper that published American cables Mr. Assange is accused of stealing — as well as Le Monde, Der Spiegel, and El País that was released recently, the government is urged to drop the charges against Mr. Assange. The papers derided the Espionage Act as an “old law” that was solely “designed to prosecute potential spies during World War I.” 

If the doings at Mar-a-Lago are any indication, the Department of Justice is anything but convinced that the Espionage Act is a dead letter. Ironies would abound should Mr. Trump and the Times find common cause in wheeling on the statute that could spell time behind bars for Mr. Trump and Mr. Assange alike.