In Kant’s moral and political writings, laws of freedom are called moral laws. There are two types of moral law. As directed merely to external actions and their conformity to law they are juridical laws; but if they also require that they (the laws) themselves be the determining grounds of actions, they are ethical laws’ (6:214).ii Kant also writes: ‘For us, whose choice is sensibly affected and so does not of itself conform to the pure will but often opposes it, moral laws are imperatives (commands or prohibitions) and indeed categorical (unconditional) imperatives’ (6:221). I understand Kant to mean that moral laws are, by definition, unconditional practical laws, which are therefore categorical imperatives for imperfectly rational beings like us.iii This raises a very broad question: how it can be the case that a juridical law is a categorical imperative? Most of this chapter will focus on a somewhat narrower question: how can a statute passed by a legislative body generate an unconditional rational requirement for us to obey?

The aim of this chapter is to demonstrate that juridical lawsiv enacted by legislators are categorical imperatives, and that the external incentives that the state links to its legal commands play a critical role in making them so. I will argue that statutory commands must be categorical imperatives if they are to establish juridical laws, and that statutes that fail to establish juridical laws do not obligate us to obey their terms.