 Raz’s explanation of the nature of law is not undermined by the fact that evaluative judgments are necessary in order to identify the implications of the social fact that Parliament prohibited vehicles from being driven without pneumatic tires. It is still possible for legal directives to have the exclusionary force that, in his theory of authority, they claim (Raz 2009, chapters 1 and 2). The court in Garner v Burr can decide whether it is an offence to pull a chicken coop on wheels without pneumatic tires, without answering the question, ‘should it be an offence to pull a chicken coop down a road on iron wheels?’, or the question, ‘should it be an offence to use a vehicle without pneumatic tires?’ But the court needs to ask the related question: ‘what is the relevant sense of “vehicle” for the purposes of this Act?’ It is what Parliament did that determines Lawrence Burr’s liability; it may take evaluative reasoning to answer the question of social fact, ‘what did Parliament prohibit, when it prohibited vehicles from being driven without pneumatic tires?’