In the sense of covering photographs in general, you don't create such a law. It's completely impractical to enforce (since photographic capture of faces is already ubiquitous in American society).
One could, hypothetically, make a law against training models on human faces. Good luck crafting that carefully enough to enforce it without undesired consequences (did we just ban training doctors on how to recognize stroke victims, or---worse---ban someone from making an automatic stroke detector that could be run on incoming patients in an ER to accelerate them to the front of the line?), but it's a better starting point than banning photographic collection of data.