Her lawsuit echoes others filed around the country by class-action lawyers who say the practice violates wiretap laws in some states. They represent email users who do not have Gmail accounts and have therefore not signed the company’s acceptance terms.

“The terms are that Google can intercept your emails and use them for direct marketing purposes,” said lawyer Richard M. Golomb, who has sued Google in Pennsylvania, Maryland and Florida. “They are also intercepting emails of the non-Gmail account holder, in violation of wiretap laws in some states.”

In court filings in the Maryland case, Google acknowledged that it routinely scans emails for spam and computer viruses, but said that’s permitted under similar federal wiretap laws.

Google argued that selling advertising based on the content of a received email is a routine business practice permitted under an exception written into the wiretap law. Google notes Yahoo and other email providers sell ads through similar methods.

“There can be little doubt that selling advertising in order to provide a free service to consumers is a ‘legitimate business goal,’” Google lawyer Michael G. Rhodes and others wrote in a Nov. 9 motion to dismiss the Maryland case. “If it were not, then the entire model by which content is provided on the Internet would be illegitimate, as would the business model by which television programming has been provided for free for the last half century.”

Courts reviewing email wiretap cases have repeatedly held that “parties expect and impliedly consent to having their communications intercepted and recorded whenever they use email,” the Google lawyers wrote. Rhodes did not immediately return a call for comment Monday.

At least one electronic privacy expert called it “a bit of a stretch” for Google to compare a search for advertising leads to rooting out spyware.

“People think when you send a message, communications companies can filter out spam and malware, and that’s correct. But filtering out spam and malware is not the same as looking at the content of the email to (find) keywords for advertising purposes,” said Marc Rotenberg, executive director of the Electronic Privacy Information Center.

“(What) if you were making a call on your Verizon cellphone, and you were talking to an Italian restaurant trying to make reservations for Friday and a Verizon agent jumped on the line and said, ‘Oh, how about this place?’” Rotenberg said. “You’re not supposed to be listening to my communications to try to sell me stuff — even if it’s a better restaurant.”

The Philadelphia plaintiff, Kristen Brinkman, does not have a Gmail account and never signed the company’s acceptance policy, according to her Nov. 30 lawsuit, which has been assigned to Senior U.S. District Judge Anita B. Brody.

Google wants the various legal disputes resolved in northern California, where the first such lawsuit was filed in June. The area is also home base for Google, which is headquartered in Mountain View, Calif.