https://www.law.cornell.edu/uscode/text/18/2257

If you google <18 usc 2257> you will see the link I copied and some others. Some of which may be of interest to you.  You should also read 2256.   Keep in mind that there have been court challenges at the appeals court level and this is not all settled law.  You are only getting the starting point from reading the original statute. 

You may want to read what these guys have to say also.  They have some 2257 stuff in their model release section.
http://thecopyrightzone.com/?tag=model-releases