I would tolerate a statement like "unable to respond to an emergency situation" - although, this varies substantially with the substance, quantity, person, and nature of the emergency. And the recognition that there are plenty of non-pharmacological situations that render you equally unfit for dealing with certain kinds of emergencies - good luck dealing with a back injury while skiing off-piste.

However, throwing out a statement like "drugs make you nonfunctional" does not help the discourse.