Last November, a 74-year-old rancher and attorney was walking around his ranch just south of Encinal, Texas, when he happened upon a small portable camera strapped approximately eight feet high onto a mesquite tree near his son's home. The camera was encased in green plastic and had a transmitting antenna.

Not knowing what it was or how it got there, Ricardo Palacios removed it.

Soon after, Palacios received phone calls from Customs and Border Protection officials and the Texas Rangers. Each agency claimed the camera as its own and demanded that it be returned. Palacios refused, and they threatened him with arrest.

Palacios, who had run-ins with local CBP agents going back several years, took the camera as the last straw. He was tired of agents routinely trespassing on his land, and, even after complaining several times, he was frustrated that his grievances were not being heard.

As a possible way to ward off the threat of arrest, he sued the two agencies, along with a named CPB agent, Mario Martinez. Palacios accused them of trespass and of violating his constitutional rights.

"My client is 74 years old, he's a lawyer, been practicing for almost 50 years, he has no criminal history whatsoever, law-abiding citizen, respected lawyer and senior citizen," Raul Casso, one of the attorneys representing Palacios, told Ars. "To have put him in jail would have been—forget the indecency of it—what a way to end a career."

The camera now remains in Palacios' attorneys' possession while they are attempting to ask the case's judge to allow them to formally introduce it as evidence.

This federal lawsuit has raised thorny questions about the limits of the government's power to conduct surveillance—in the name of border security—on private property, without the landowner's permission.

"As a matter of policy, CBP does not comment on pending litigation," Jennifer Gabris, a CBP spokeswoman, emailed Ars.

The Texas Department of Public Safety similarly declined comment.

In court filings, Texas officials have claimed qualified immunity, a legal doctrine that protects law enforcement officials.

The border isn’t where you think it is

Palacios' ranch is situated at the 35-mile marker due north from Laredo, along Interstate 35, just three miles south of the small town of Encinal. The nearest US-Mexico border crossing is at Laredo.

The precise distance between the border and Palacios' ranch matters: under federal law, agents can go onto private property that is within 25 miles of the border "for the purpose of patrolling the border to prevent the illegal entry of aliens into the United States."

In other words, if Palacios' ranch were within that range, he likely wouldn't have a case.

This is related to, but distinct from, the 100-mile radius that the CBP claims it can operate in and warrantlessly stop people and search bags, cars, electronic devices, and more. This is commonly referred to as the "border exception" to the Fourth Amendment, which protects against warrantless searches and seizures. (There is currently a lawsuit over border searches of electronic devices underway in federal court in Massachusetts: Alasaad v. Duke.)

As Palacios alleges in the civil complaint, his interactions with CBP began in April 2010 when his two sons were stopped at a checkpoint along I-35. When one son, Ricardo Palacios Jr., refused to answer questions, he was taken to a secondary inspection where he was assaulted by a CBP officer. Eventually, after being detained for 90 minutes, he was driven home to the ranch just a few miles away.

Over the next several years, CBP agents roamed "freely about, day or night" on the Palacios ranch, despite his numerous efforts to protest. He even sent a formal letter to a regional CBP supervisor on April 9, 2010. However, the letter doesn't seem to have made any substantive difference.

A cycle of CBP agents making incursions onto the ranch and Palacios telling them to leave continued for years—that is, until he found the camera.

"Plaintiffs maintain that there is something creepy and un-American about such clandestine, surreptitious, 1984-style behavior on the part of Defendants—officers of the law," Palacios argues in the complaint.

Palacios and his attorneys believe that the camera is part of "Operation Drawbridge," an effort by the Texas Department of Public Safety to use "low-cost, commercially off-the-shelf technology that has been adapted to meet law enforcement needs," with "hundreds of cameras located along the border."

The cameras, which are in constant use, 24 hours a day, send alerts to the Border Patrol as well as state and local authorities.

"At approximately $300 per camera, they provide a high-tech capability at a low-tech cost," the Texas DPS website states.

The Texas DPS did not immediately respond to Ars' request for comment.

Since the lawsuit, Casso said, his client has only had one interaction with CBP: agents went to his door and asked his permission to pursue a group of people they believed were on his ranch and were undocumented. He agreed.

"Apparently, this lawsuit has rang their bell," Casso said. "On the one hand, it's good they're protecting us, but on the other hand, they're violating the Constitution. We have reason to believe that there are 4,000 cameras deployed throughout the region. Could there be more? Possibly."

Casso was quick to underscore that he was not suggesting that property owners within the border region go searching for similar cameras on their own land.

"That's their private business, not mine," he said.

The judge in the case, US Magistrate Judge Guillermo R. Garcia, has not scheduled any hearings for now.

"Our lawsuit is that we want a federal judge to tell the border patrol and the feds to not go on [Palacios'] property without permission or probable cause," David Almaraz, Palacios' other attorney, told Ars. "And if you all are going to keep doing that, you're going to have to pay for it. It's called the right to be left alone. That's what the Fourth Amendment is all about."