Duke University’s Appellate Litigation Clinic, which relies on the work of law school students, won an appeal brought to the U.S. Fourth Circuit Court of Appeals, which covers North Carolina.

The case centers on what’s known in legal terms as “curtilage” — the land immediately surrounding and associated with homes, such as an outdoor patio, which is protected from government intrusion. In an opinion issued last month in U.S. v. Christopher and Lela Covey, a three-member panel of Fourth Circuit judges declared that a law enforcement search of the Coveys’ private backyard patio was unconstitutional without a warrant.

The Coveys live in a privately set home in the rural village of Valley Grove, W.Va. In 2009, a law enforcement search turned up marijuana, and Christopher Covey was charged with manufacturing marijuana. He was sentenced to one to five years of home confinement.

In 2011, the Coveys sued several county officials, including the sheriff, arguing that by entering their private patio, law enforcement agents violated their 4th Amendment rights. The District Court out of West Virginia dismissed their complaint, prompting the Coveys’ appeal.

On Oct. 21, 2009, a deputy for the county tax assessor entered the Coveys’ property to collect data to assess their home’s value. The home was protected by trees and “No Trespassing” signs along their private driveway. Finding no one inside, the tax assessor searched the backyard patio, where he found marijuana. He contacted the the county sheriff. Two law enforcement agents went to the home to investigate. They parked their car in the Coveys’ private driveway, entered the patio and saw Christopher Covey at his workbench. After obtaining a search warrant, the officers seized evidence and arrested the Coveys.

The county argued that the search was tantamount to the “knock-and-talk” technique, which doesn’t violate the 4th Amendment. The officers claimed that they were justified in bypassing the front door because they saw Christopher Covey on the patio.

But the Coveys argued that the only way for the officers to have observed Covey at his workbench was if they were standing directly on the patio, where they had no legal right to be. And the Court of Appeals agreed. “[T]he right to knock and talk does not entail a right to conduct a general investigation on a home’s curtilage,” Circuit Judge Henry F. Floyd wrote in the opinion.

The Duke students worked on the case during the last academic year. It was argued to the circuit judges last October by clinic director Sean Andrussier.