As quite a few have noted, the legal use depends on where you are. I like the design, they seem very sensible. However, I know that areas in drought frequently ban all wood fires. The issue is sparks and the coals / hot ash. I would assume that when you burn pine cones or sappy wood, sparks would come out the chimney (I could be wrong, having never seen one in use). When you are done using, the hot ash needs to be put somewhere, hopefully in a fire ring. At that point, it is not much different than if you built the fire in the fire ring in the first place. Most Rangers wouldn't differentiate between the two, the end result is the same. The Ranger wouldn't know if you had or planned to made sure the ash was cool before you left the area. They standardize the rules and the knowlegable have to suffer because fools camp.