Yes you can get a DUI after smoking and driving. Technically if you are tested for drugs for any reason at a police stop, and have the drug in your system, you CAN be arrested for drugged driving. Marijuana, even as prescribed, is still considered a drug you can not drive on. Such as, you could still get arrested for driving on pills you are prescribed to. It would depend on the officer and if they want to arrest you or believe you are impaired and guilty of drugged driving.