&gt; That&#x27;s not true in the slightest, drunken driving laws don&#x27;t measure the drivers impairment but BAC.<p>They measure the impairment and BAC is an instrument to that. Otherwise it would be of no interest. There used to be other impairment tests, like walking the line, before breath testers became commonplace.<p>&gt; And in any case, attempt implies intent.<p>As manslaughter is an unintentional killing, I thought the metaphor was fairly obvious.<p>You know drunk drivers are prone to committing manslaughter other variables being equal, you do it anyway: well that&#x27;s an attempt. Rationale behind it is irrelevant, just like noone cares you needed those money badly when you killed that cashier.