The 9th U.S. Circuit Court of Appeals agreed with a lower court that rejected Google's argument that having its vehicles, which rolled through neighborhoods around the world, secretly collect email addresses, passwords, images and other personal information from unencrypted home computer networks was exempt from the federal Wiretap Act.
Google had argued non-password-protected WiFi networks were just like "radio communications" and were "readily accessible to the general public."
Radio communication is not covered by the wiretapping law.
The unanimous, 35-page decision by a three-judge panel said Google was in effect trying to invent definitions of words in the hope of getting its actions declared legal.
"In common parlance, watching a television show does not entail 'radio communication,'" Judge Jay Bybee wrote for the San Francisco court. "Nor does sending an email or viewing a bank statement while connected to a WiFi network. There is no indication that the Wiretap Act carries a buried implication that the phrase ought to be given a broader definition than the one that is commonly understood."
People can buy special equipment to get that personal information, but that doesn't make them readily accessible to the general public, the court said.
"Surely Congress did not intend to condone such an intrusive and unwarranted invasion of privacy when it enacted the Wiretap Act 'to protect against the unauthorized interception of electronic communications,'" Bybee wrote for the court.
Google Street View is a technology featured in Google Maps and Google Earth that provides panoramic views of streets and roads. It was started in 2007 in several U.S. cities and has since expanded to cities and rural areas worldwide.
Besides photographs, Street View vehicles secretly collected the emails and other personal information from unencrypted home computer networks -- a practice known as "payload sniffing."
"We are disappointed in the 9th Circuit's decision and are considering our next step," a Google spokeswoman said.
Its options include settling the case, going back to the lower court for trial, asking the entire appeals court to rehear the case or petitioning the U.S. Supreme Court to review the decision, Wired magazine said.
The 22 plaintiffs are each asking for $10,000 along with unspecified punitive damages, The New York Times said.
Plaintiff attorneys said they would now like to get the case certified as a class-action lawsuit, which would allow millions to join, an attorney told the Times.