A week after Google failed to convince a judge that Gmail keyword scanning didn't violate wiretap laws, Yahoo has also been slapped with a class-action privacy lawsuit. A pair of non-Yahoo users say that by scanning incoming emails to serve more targeted ads, Yahoo was effectively intercepting and reading their mail. As non-users, they argue that they didn't agree to the searches, and they're filing suit on behalf of all other Americans who sent mail to Yahoo.

The case isn't exactly like the class-action suit against Google — which included Gmail account holders as well as non-users — but it uses the same basic argument, and Yahoo will likely mount a pretty similar defense. Google argued that if you were sending emails to one of its users, you implicitly understood that Google was going to scan them and that you were voluntarily giving up information to a third party, which removes the legal right to absolute privacy. It also said that scanning emails was a standard part of its business model, which could theoretically let it off the hook.

Judge Lucy Koh, however, said that Google's arguments weren't strong enough to get the suit automatically thrown out, and Yahoo may face the same problems. If the case is successful, the plaintiffs are asking a judge to stop Yahoo from continuing to scan emails and pay damages under both US and California law. That, however, is a long ways away. The case hasn't even been certified as a class action suit yet, and Google hasn't lost its case either, so the precedent is far from clear. As GigaOM notes, Yahoo was fighting a similar suit in 2012, before it was voluntarily dismissed early this year.