One legal issue in the case was whether Facebook could be said to have authored the statements that informed users that the plaintiffs had "liked" a particular brand.

The plaintiffs' attorneys did not respond to a request for comment Tuesday. Both Facebook and its lawyers declined to comment.

Sponsored Stories began as a desktop feature. In March, the company began delivering Sponsored Stories in mobile users' news feeds, the first advertising to come to Facebook's mobile app.

The IDG News Service