He concluded that the exemptions built into the Federal Wiretap Act did not apply to Google's snooping.

"The Court finds that Plaintiffs plead facts sufficient to state a claim for violation of the Wiretap Act," Ware wrote in his ruling. "Defendant's contention that Plaintiffs fail to state a claim for violation of the Wiretap Act, as Plaintiffs plead that their networks were 'open' and 'unencrypted,' is misplaced."

Jim Dempsey, the vice president for public policy at the Center for Democracy and Technology (CDT), a Washington D.C.-based advocacy organization, said that intercepting data communications from a Wi-Fi network, even one unsecured with a password, "should certainly be illegal."

But he also argued that Congress needed to clarify the law. "It's certainly far preferably to clarify the statute legislatively," Dempsey told Computerworld on Friday, rather than require judges like Ware to parse the ambiguous and outdated language of the 25-year-old Electronic Communications Privacy Act (ECPA). "But whichever way this case comes out, clarifying the statute on this particular point is not going to be easy."

Google said it was considering its next move.