Since Donald Trump’s inauguration more than two years ago, Alex Mensing, a volunteer with the immigrant rights group Pueblo Sin Fronteras, has been pulled into secondary screening nearly 30 times at U.S. ports in the San Diego-Tijuana area, as well as the Los Angeles airport. His longest interrogation, in late 2018, spanned roughly four hours. It was hardly an isolated experience, Mensing told me. “Pretty much every member of Pueblo Sin Fronteras who crossed the border was interrogated during that time,” he said. An Intercept investigation in February uncovered the backstory to those interrogations, revealing that Pueblo Sin Fronteras was targeted in a secretive joint U.S.-Mexican intelligence gathering operation, which also swept up immigration attorneys and journalists working along the border. NBC News later obtained documents showing that the operation was carried out by officials within U.S. Customs and Border Protection, the Border Patrol, Immigration and Customs Enforcement, and the FBI, and included a secret database made up of 59 activists, journalists, attorneys, and unspecified others. At least 10 of the government’s targets were volunteers with Pueblo Sin Fronteras. Mensing was one of them.

While CBP eventually admitted to the operations, which sparked multiple internal and congressional investigations, the federal law enforcement agencies involved have emerged from the episode largely unscathed. Mensing is hoping to change that. On Wednesday, he joined two other plaintiffs, represented by the American Civil Liberties Union and Kirkland & Ellis, in filing a lawsuit against CBP, ICE, and the FBI for violations of their First and Fourth Amendment rights. Though Mensing and his co-plaintiffs “did not commit any crime, violate any customs or border regulation, or engage in any other activity that could reasonably give rise to a suspicion of criminality,” the ACLU alleged, they nonetheless “faced repeated and prolonged detentions and interrogations at the border.” “The government’s powers are not limitless,” the complaint, filed in the U.S. District Court of Arizona, read. “It cannot target people for intrusive surveillance, detention, searches, and interrogation because of their expressive political activity protected under the First Amendment. And it cannot use its border control powers — to regulate the import of goods, verify travelers’ identities, and stop the entry of contraband — to conduct suspicionless fishing expeditions for criminal activity unconnected to border enforcement that it could not conduct within the country.” The Trump administration’s border enforcement agencies illegally and unconstitutionally exploited their border enforcement authorities, the complaint went on to say, by “directing surveillance, detention, intrusive searches accompanied by excessive physical restraint, and intensive interrogation at the border” against individuals “because of their lawful humanitarian activities.” Criminalizing Compassion The ACLU’s suit comes one year after thousands of migrants, most from Central America, made their way by caravan to the U.S. border. Some were running from the violence and instability of their home countries, others were fleeing the devastating impacts of the climate crisis on the rural communities they called home. Families with children traveled together, seeking safety in numbers as they navigated stretches of Mexico where kidnapping, extortion, and murder of migrants are entrenched problems. Though it was not the first, the October 2018 caravan prompted a furious response from Trump, who deployed more than 5,000 troops to the border. “Operation Faithful Patriot” was initiated just in time for the 2018 midterm elections. Later changed to “Operation Secure Line,” it was the same campaign under which the surveillance of journalists, lawyers, and advocates was justified. In the months that followed, U.S. border security forces twice launched tear gas into Mexico in response to the caravan, once in November and again on New Year’s Eve. Both times, women and children were caught up in the gassings. As The Intercept’s and NBC’s reporting revealed, the U.S. also ramped up scrutiny of advocates, lawyers, and journalists working in the Tijuana-San Diego area. Mexican law enforcement snapped photos of the passports of photojournalists working near the border wall. When asked who they were taking the images for, the Mexicans replied, “For the Americans.” The photojournalists were later pulled into secondary screening as they attempted to reenter the U.S. Their images and electronics were searched, and they were pumped for information about the caravan and the activists working with the migrants. Two award-winning photographers were denied reentry into Mexico, barring them from the place where their journalistic work was focused. Immigration attorneys with the prominent border law firm Al Otro Lado were similarly denied reentry. They filed their own lawsuit, also with the ACLU, challenging the government’s actions earlier this year. By late 2018, interrogations of Pueblo Sin Fronteras’ volunteers had become the norm. Volunteer Jeff Valenzuela, Mensing’s co-plaintiff in the ACLU suit, got it particularly bad. A U.S. citizen living in Tijuana with family in California, Valenzuela told his story of border harassment for the first time in an interview with The Intercept earlier this year, explaining how he had been sent to secondary screening a half-dozen times from December through February. In one of the instances, which occurred on Christmas Day as he was attempting to visit his family, border guards searched his phone and he was held for roughly 2 1/2 hours. When Valenzuela attempted to cross the border again days later, he was taken to a concrete cell and shackled to a steel bench for approximately five hours. For Mensing, the intensification of interrogations became too much. “I just got fed up with it. I was tired of getting detained. I was tired of getting interrogated. I was concerned about further retaliation. I was concerned it would escalate,” he said. “And so, I did not go to the United States from January until September.”