The laws surrounding this depend on the jurisdiction of where the adult cams are hosted.
The reason for all this regulation has to do with the content that can be found in these live rooms.
Of course, you are required to be over 18 years of age to visit them.
Some jurisdictions actually require that you be 21 years of age to participate in these websites.
Not only do they have sexually explicit chat messages going on back and forth, but now they have adult cams as well.
This means that users are likely going to these rooms and showing themselves naked on a webcam for everybody else in the room to see.