I agree with the above. Not to belittle the importance of and FFDO, but the scope of their authority as a Federal OFFICER is limited to theor duties when operating the flight.
And if anyone thinks that citizens have the right to make traffic stops AT GUNPOINT just because you've seen a vehicle swerving, is dead wrong, retarded, or both. Putting yourself in a situation like Clay did is incredibly wreckless behavior. What should an average citizen or even an FFDO do in this situation? Humm... Maybe get the plate number, follow the car, and call the police to report what's going on if you really think the driver is placing others in immediate danger.
If anyone thinks that what this guy did was reasonable and prudent at the time, you need to grow up. Stop watching Hollywood cop shows and please don't ever carry a firearm.