 A first reason for recognizing marriage should be set aside. This is that the monogamous heterosexual family unit is a natural, pre-political structure which the state must respect in the form in which it finds it (Morse 2006; cf. new natural lawyers, Girgis et al. 2010). But, whatever the natural reproductive unit may be, marriage law, as legislation, is constrained by principles of justice constraining legislation. Within most contemporary political philosophy, the naturalness of a given practice is irrelevant; indeed, in no area other than the family is it proposed that law should follow nature (with the possible exception of laws regarding suicide). Finally, such objections must answer to feminist concerns that excluding the family unit from principles of justice, allowing natural affection to regulate it, has facilitated inequality and abuse within it (see section 5).