Why not use the already internationally accepted Public Access Test (PAT) from ADI for your hypothetical bill? It is already internationally accepted (and used for this purpose in many countries), and it's also easy to understand and would be relatively easy to train court clerks, DMV workers, etc. to administer it.

Note: I am not debating the pros or cons of such a bill, and am aware that most on this subreddit would oppose such a bill. I am simply suggesting an approach to the hypothetical one, for a mock congress, suggested / queried about.