A U.S. consumer advocacy group has reignited the debate over online privacy after it unearthed a court document in which Google argues that anyone sending messages to Gmail’s 425 million users should not expect privacy.

The court document is from a U.S. class-action lawsuit in which a group of non-Gmail users accuse Google of breaking laws on wiretaps by scanning emails so that the company can target ads to users – a key component of the company's business model.

"Just as a sender of a letter to a business colleague cannot be surprised that the recipient’s assistant opens the letter, people who use web-based email today cannot be surprised if their communications are processed by the recipient’s ECS [electronic communication service] provider in the course of delivery," the court papers say.

In its filing, Google also cited a 1979 court decision on tracking phone numbers, which stated that "a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties."

John Simpson of Consumer Watchdog, the advocacy group that discovered the court document, said it suggests that "Google has finally admitted they don’t respect privacy."

Media outlets in a number of countries picked up the story, prompting Google to issue a statement on Wednesday.

"We take our users' privacy and security very seriously; recent reports claiming otherwise are simply untrue. We have built industry-leading security and privacy features into Gmail – and no matter who sends an email to a Gmail user, those protections apply."

A hearing in the class-action lawsuit is scheduled for Sept. 5.

Shocking admission, or not?

Nate Cardozo, a staff attorney with the Electronic Frontier Foundation, said he wasn’t surprised by Google’s legal argument.

"Google does more processing than most, but every email server processes emails that come in," Cardozo said by phone. "Someone who runs an email server has to, as a matter of the technology."

'It’s alarming for the world’s largest email service provider to say that they don’t have an obligation to protect privacy.'—Marc Rotenberg, privacy lawyer

He said many email providers scan messages for viruses or spam, while Google has a track record on privacy issues. For example, unlike a number of other major internet companies, Google requires a warrant before it will release data to the U.S. Department of Justice.

Other experts say that Google’s handling of the lawsuit should be taken seriously, even if it has to do with automated processing of email for ads.

"It’s alarming for the world’s largest email service provider to say that they don’t have an obligation to protect privacy," said Marc Rotenberg, who has taught privacy law for 25 years and heads the Electronic Privacy Information Center in Washington, D.C.

He said the lawsuit is noteworthy because, while Gmail users may have consented to having their emails scanned by Google by agreeing to the company’s terms of service, non-Gmail users have not provided consent.

Heightened attention to online privacy

The lawsuit against Google, which was filed in May, alleges that the company "unlawfully opens up, reads, and acquires the content of people's private email messages."

It’s not surprising the civil case is garnering attention given its timing in the wake of Edward Snowden’s revelations about online spying by the U.S. National Security Agency (NSA), said Andrew Clement, who runs the University of Toronto’s information policy research program.

A series of news reports in recent months revealed that the NSA has been secretly collecting massive quantities of information online for years, by accessing the networks of major U.S. internet companies.

"There’s much more acute attention to these issues of privacy and surveillance, who has access," Clement said. "That I think adds to the significance of Google’s statement."

Micheal Vonn, policy director at the B.C. Civil Liberties Association, said the court filing highlights the tension between the company’s stance on user privacy and its business model.

"Google can’t have it both ways. It can’t say in terms of this lawsuit, you have no reasonable expectation of privacy in your emails and say at the same time that it is effectively guarding your privacy ‘very seriously,’" she said by phone.

"The simple fact here is that the business model has always been to capitalize on selling to advertisers, on the basis of the content of your information."