I believe that back in the 1980's the U.S. was a signatory to an international treaty that made the nation from which a spacecraft was launched libel for any damages caused by that craft. There were some outcries at the time because it effectively gave NASA an ironclad monopoly. Also the way the U.S. government implemented it specified rockets needed a permit for launche, rockets of any size. One of then model rocket companies began to include the proper permit forms with each engine. After the deluge of forms a minimum size was put on the rocket to need the permit.