Mike Blake / Reuters

This is the story of an effort to safeguard the First Amendment.

In the fall of 2018, five American photojournalists began going on trips to Mexico to gather news about the caravan of Central Americans migrating through that country. At the end of each reporting trip, they returned to the U.S. through official ports of entry. Coming home ought to have been easy. These were law-abiding citizens traveling for one of the few kinds of work that are specifically protected by the Constitution. Instead, U.S. border officers kept referring them to secondary inspection and asking them intrusive questions about their work that struck them as having no legitimate purpose.

The civil rights and liberties of American citizens are especially vulnerable to violation at ports of entry, where bureaucrats have tremendous discretion to detain, search, and question individuals and to delay their repatriation. At best, reentry into the United States is a tiresome drag, known to everyone who has stumbled wearily from an overnight flight only to stand in an understaffed customs line. That burden and the potentially intrusive government searches associated with it are ostensibly justified by the need to combat problems as varied as undocumented immigration, child trafficking, terrorism, the spread of agricultural diseases and invasive species, and the smuggling of narcotics and of goods with duties attached to them.

But the photojournalists found it improbable that they were suspected of breaking any laws. Were they being targeted because they were members of the press? Was the government trying to obtain access to their source lists and the intelligence they’d gathered in the course of their reporting? Suspicions to that effect were bolstered when The Intercept reported on an apparent pattern: U.S. and Mexican authorities seemed to be coordinating harassment of the journalists. Then a leak from an anonymous source at the Department of Homeland Security added clarity. “The [U.S.] government had listed their names in a secret database of targets, where agents collected information on them,” an NBC affiliate in San Diego reported. “Some had alerts placed on their passports, keeping at least two photojournalists and an attorney from entering Mexico to work.”

If accurate, that is a serious abuse of power: The government allegedly jeopardized the livelihood of these journalists, as well as their ability to relay useful information to Americans. A government spokesperson told CNN at the time that Customs and Border Protection “does not target journalists for inspection based on their occupation or their reporting.” But in one case, a Mexican border official who turned one of the photojournalists away told her he was doing so at the behest of the American government.

Now the photojournalists are suing three federal border agencies. Their complaint, filed this week in federal court, alleges several related violations of their civil rights. They were subject to questioning that “substantially burdened Plaintiffs’ First Amendment rights to freedom of speech, association, and the press,” the lawsuit asserts, requiring them “to disclose confidential information about their observations, sources of information, and/or work product, including the identities of individuals with whom they may have interacted in the course of their work as journalists.”

The American Civil Liberties Union, which filed the lawsuit on their behalf, stated Wednesday that “border officers at ports of entry may ask questions relating to immigration or customs, but they may not use border screening as a pretext to interrogate journalists about their work.”

Journalists often possess information that would be valuable to competing ideological factions in the federal government and to various members of the federal bureaucracy. If they are forced to compromise sources or to turn over information every time they enter the United States from abroad, the task of news-gathering will become significantly more onerous, some activity protected by the First Amendment will be chilled, the public will get less information, and the free press that the Framers tried to protect will be weakened.

News-gathering is unusual among occupations in that it’s specifically protected by the Constitution. If even members of the press, with their ability to raise distinct First Amendment claims, are subject to harassment at the border, the abuse of power is unlikely to end there.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.