What do you get when you combine family trips to a gardening store and loose-leaf tea in your trash? To Kansas law enforcement, it’s probable cause to get a search warrant and perform a SWAT-style raid on a private home. In 2011, Robert Harte and his 13-year-old son went to a store for hydroponic equipment to grow tomatoes for a school project. A state trooper had been assigned to watch that store and write down the license plates of any customers (apparently, shopping at a gardening store translates to marijuana production). To follow up that stellar bit of police work, the Johnson County Sheriff’s Office twice examined the Hartes’ trash. They found, both times, an ounce or so of “saturated plant material.” The Keystone Kops couldn’t tell the difference between tea and tokes using their senses, so they field-tested the substance and the test came back positive for marijuana. (“A partial list of substances that the tests have mistaken for illegal drugs would include sage, chocolate chip cookies, motor oil, spearmint, soap, tortilla dough, deodorant, billiard’s chalk, patchouli, flour, eucalyptus, breath mints, Jolly Ranchers and vitamins,” notes Radley Balko.) Still, after falsely reading the tea leaves, the deputy sheriffs performed a military-style raid on the family home. At 7:30am, the Hartes were woken up by pounding on their doors; as soon as Mr. Harte answered, an armed team flooded into the room, ordered him to the ground, and rifled through the home for three hours. The officers—once they realized that there was no large-scale growing operation—began searching for “any kind of criminal activity,” a far greater sweep than a warrant to search for “marijuana” and “drug paraphernalia” permits. Moreover, the deputies left the canine units in the house longer than was necessary, to give them “training or just experience”—so the terrifying armed raid was a mistaken fishing expedition that then turned into a training exercise. Cato has filed an amicus brief in the federal appellate court where the Hartes’ lawsuit against the police is currently pending (after the district court dismissed it). We argue that the police failed to knock and announce their presence in anything but a literal sense—an important Fourth Amendment rule—and also exceeded the scope of their warrant to look for “any criminal activity.” The case thus raises pressing issues of police militarization in society and warrantless police authority. In briefing for an earlier case, Cato noted that “SWAT team deployments have increased more than 1,400% since the 1980s.… SWAT teams and tactical units were originally created to address high-risk situations, such as terrorist attacks and hostage crises. Today, however, these extreme situations account for only a small fraction of SWAT deployments; they’re used primarily to serve low-level drug-search warrants.” Moreover, the knock-and-announce rule is an ancient one rooted in the English common law dating back to the early 17th century. The rule serves to protect the life, limb, and property of both home occupants and police serving a search or arrest warrant. When officers use the force associated with a SWAT raid, even without literally breaking the door, their pro forma compliance with the knock-and-announce rule converts the Fourth Amendment into a “parchment barrier.” Indeed, the systemic use of SWAT-style force to execute low-risk drug warrants converts the presumption that people normally peaceably comply with police—central to the knock-and-announce rule—on its head. The police here could easily have investigated their suspicions here without going commando. Accordingly, we call upon the U.S. Court of Appeals for the Tenth Circuit to send this case back for trial, consistent with the common law underlying the Fourth Amendment.