Not sure, but i may have a answer. My step daughter works for the COE at lake Cumberland and i ask her this question. She is one of the people that promotes the use of PFD and safety. Her response is, when the law was made the theory was that while in the water that you could put on a vest and get it buckled, however, when a inflatable expands it is so tight and buoyant that it is nearly impossible to put it on while in the water.