The joke is in treating the &quot;or&quot; as the Boolean operator and collapsing it into a yes-no question.<p>Thus, the answer would be &quot;no&quot; if and only if legalization has had no effect whatsoever.  As the asking of the question implicitly assumes that there has been an effect, answering yes therefore responds to the question in a very literal, truthful way, without actually conveying any new information.<p>This is my favorite way to punish a poorly structured interrogatory.  It forces the follow-up question, &quot;Which one?&quot;  Which can then be answered with &quot;both.&quot;<p>Some people say that there are no stupid questions, but clearly, some questions are more intelligent than others.