Epilepsy, or a seizure disorder, completely precludes a psychophysical evaluation for intoxication because all of the signs and symptoms used as indicial of intoxication are most likely due to the seizure and the postictal state.
Additionally, a person in a postictal states is not fully cognizant so they cannot make a knowing and voluntary decision regarding consent or refusal to give consent.
{Observations/Psychophysicals and Refusal}