So if a faster shoe came along (Vapor Fly 5%) that didn’t use a plate, that would be okay? But if people preferred the Vapor Fly 4% over the faster shoe, they couldn’t use it because of the plate? . . .

The patent application Ross Tucker cites has close to zero applicability. Nike has been working on a different energy return “spring” shoe that probably would be illegal - the patent could be for those shoes. And people claim lots of things in patents, that doesn’t make the claims true. All shoes have some combination of firmness and cushioning, and shoes have used an embedded firm plate design before, and nobody complained.

What if a biomechanics lab proved the Vapor Fly 4% is not acting as a spring but makes runners more efficient through some other mechanism (firm underfoot feeling but lots of cushioning)?