I guess something like this is sortof no-mans lands as far as the laws are concerned then.
I'm sure that's true - particularly because it is completely enclosed, unlike other two-in-front three wheelers like the Bombardier/Can-Am, the new Harley conversion kit with the one rear wheel
http://scorpiontrikes.com/ and the Piaggio scooters you see everywhere in Paris.
The Polaris Slingshot I see as more car–like the Elio, in spite of it being topless, partly because you are riding in, not on, it. Helmets should no more be required by law than in any open top sports car–plus, it does have rudimentary roll bars.
Another looming no man's land in the field of transportation is the high power electric bicycle sure to be around the corner.
