SAN FRANCISCO — Despite a class-action settlement in August that was supposed to ensure that Facebook users clearly consent to their comments, images and “likes” being used in ads, it has been business as usual on the service.

If you are among Facebook’s 1.2 billion users, the company says, you are automatically consenting to such social ads. Opting out is impossible for some ads, and for others, the control to stop them is buried deep within the service’s privacy settings.

But on Thursday, the nonprofit advocacy group Public Citizen will try to step up the pressure on Facebook to change its practices. In a legal brief to be filed with the Ninth Circuit Court of Appeals in San Francisco, the group will contend that the settlement violates the laws of seven states, including California and New York, by failing to require Facebook to receive explicit permission from parents before using the personal information of teenage users in advertising.

Image A Facebook social ad.

“The default should be that a minor’s image should not be used for advertising unless the parent opts in. Putting the burden on the parent to opt the child out gets it exactly backward,” said Scott Michelman, a lawyer at Public Citizen, which has filed the appeal on behalf of five parents and their children who use Facebook.