A federal appeals court has reversed an accountant's tax-evasion conviction because the government seized his computer data and held it for more than 2.5 years—a breach of the constitutional right to be free from unreasonable searches.

The 2nd US Circuit Court of Appeals ruled last week that the government's tactics against the Connecticut accountant amounted to an "unreasonable seizure." The authorities seized the accountant's records while investigating alleged illegal activity of his clients. But they continued holding the data for years and later brought charges against the accountant, who was not the target of the original investigation.

"If the government could seize and retain non-responsive electronic records indefinitely, so it could search them whenever it later developed probable cause, every warrant to search for particular electronic data would become, in essence, a general warrant," Judge Denny Chin wrote for the appeals court.

At least one digital rights group said the decision may affect the National Security Agency's vast electronic snooping programs disclosed by whistleblower Edward Snowden.

"I would certainly argue that it calls into question the whole collect-it-all-and-sniff-through-it-later practice," Hanni Fakhoury, an attorney with the Electronic Frontier Foundation, told Courthouse News Service.

The accountant's data was seized in 2003 pursuant to a valid warrant. But in 2006, the authorities began developing a case against the accountant. The feds examined more of the data, obtained a warrant, and then brought charges of alleged tax evasion. The man was convicted and sentenced to two years. His sentence was stayed pending appeal.

"The Fourth Amendment was intended to prevent the government from entering individuals' homes and indiscriminately seizing all their papers in the hopes of discovering evidence about previously unknown crimes," Chin wrote. "Yet this is exactly what the government claims it may do when it executes a warrant calling for the seizure of particular electronic data relevant to a different crime."