You do realize that there is licensing for engineers already? It's on a state by state basis in the US although there is a national organization. It's mostly relevant to the degree that you deal with regulatory bodies and have to sign off on drawings, reports, etc.

In my first job out of school I worked on offshore drilling rig design and retrofits. I took an engineer in training exam and would have eventually gotten a PE (Professional Engineer) license had I continued in that field because you had to submit designs to the ABS and other governmental organizations.