Hunter Hollingsworth was driving through his rural Tennessee property one morning when he saw something sparkle.
"I thought it was a raccoon or a possum, shining in a tree. Then I realized it was a camera with an antenna," Hollingsworth, 32, recalled of the 2018 incident.
Hollingsworth, a railroad technician, lives about 10 minutes from the family-owned 93-acre property in Benton County, spread across the Big Sandy River.
Confused, he took the camera down and put it in a safe – until months later, when state and federal officers arrived at his home, brandishing a search warrant and looking for the equipment.
It turned out state and federal wildlife agencies had hung the camera on his property, Hollingsworth said, seeking evidence that he was breaking conservation laws.
Though he acknowledged breaking one such rule, Hollingsworth said the camera was an invasion of privacy. Experts say the legalities involved go beyond wildlife conservation, touching on policing, online privacy and more.
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"They were surveilling every time I came and left, so they could come and check me every time I hunted," Hollingsworth said.
The issue highlights a century-old, but little-known legal interpretation that allows access to private property without a warrant – even to set up surveillance cameras.
The US Constitution prohibits unreasonable searches of "persons, houses, papers, and effects", but the Supreme Court has interpreted that to mean that while officers require a warrant or just cause to search a home, legal protection does not extend beyond the house's immediate vicinity. This is called the open fields doctrine.
"The doctrine is in serious need of attention as it gives license to law enforcement that is inconsistent with constitutional guarantees," said Barry Friedman, a law professor and director of the Policing Project at the New York University School of Law.
A federal judge cited the open fields doctrine to throw out a case brought by Hollingsworth seeking to protect the privacy of his land. But he tried again in a state court and a Tennessee judge last year ruled that game wardens could not enter private land without a warrant.
Tennessee is appealing that verdict, but the Tennessee Wildlife Resources Agency is now obtaining search warrants or landowner permission before entering private property, the agency's communications director Emily Buck said.
Now the lawyer who spearheaded the case is trying to push other states with similar provisions and has begun another lawsuit in Pennsylvania.
"This is police state-style tactics, treating people's private spaces as presumptively open to prying eyes and surveillance," said Joshua Windham, the attorney behind the cases for the Institute for Justice, a nonprofit, libertarian law firm.
The Pennsylvania Game Commission referred questions to the state attorney general's office, which declined to comment on ongoing litigation.
The open fields doctrine, Windham said, came out of the federal government's 1920s prohibition on alcohol and its 1980s "war on drugs".
Federal agents use it, for instance, to access private property for chemical sampling, to check crops or patrol for illegal immigration, he said.
"You can put up a fence and sign, and that would have no impact on an officer's ability to enter a property without a warrant ... and look around for evidence that you've done something wrong," he said.
Yet conservation enforcement is unique in that wildlife does not belong to a landowner, said Richard Simms, a former Tennessee game warden.
"If officers can't go where the wildlife lives, they can't protect it," he said. But in this case, wildlife authorities had gone too far by setting up cameras without warrants, said Simms.
Originally the open fields interpretation envisaged enforcement agents physically entering private land looking for evidence, Windham said, not setting up remote surveillance.
"It's not surprising to learn that when you give government officials unlimited power to surveil private land that they'll not just walk around – they'll put up cameras."
The US Fish and Wildlife agency did not respond to a request for comment.
'THE FRAMEWORK JUST DOESN'T FIT'
The open fields doctrine also arose at a time when most Americans lived in rural areas, said Carrie Leonetti, a professor at the University of Auckland and expert on the intersection of science and the law.
"It's when the average person stopped living on farms and moved into suburban areas that this got really baffling," she said.
Courts have had to wrestle with how these powers apply to suburban yards, apartment buildings and even homeless encampments.
"The framework just doesn't fit with the vast majority of the ways that people live now," Leonetti said.
There are also rising questions about how this legal gray area extends online, she said, for instance to data mining and whether people have a right not to have their public data aggregated and analysed.
"I don't care that the gym knows when I swipe in, but you could take those pieces of information and put them together into a mosaic," she said, a prospect that gets only more concerning with the introduction of automatic facial recognition.
For Hollingsworth, the whole experience has shaken his understanding of privacy.
"If I'm on a road on my property, I wouldn't expect privacy," he said.
"But if I'm in the woods or in a field that you'd have to be on my property to see, I would expect that to be private."