  A number of other possible constraints on the criminal law have been proposed (Dan-Cohen 2002, 150–171; Ripstein 2006). As mentioned earlier, some are skeptical of all such principles. To determine the limits of the criminal law, they think, we must refer to a ‘more disorderly set of considerations’, none of which gives us anything as simple as a (set of) constraint(s): the resulting account of criminal law’s limits will be ‘messier’ than its rivals; but this is ‘what the messy worlds in which we live require’ (Duff et al 2014, 51–52). The correct response to this skepticism remains unclear. One possibility is that a defensible general line can indeed be found. The question is where the line is, and how it is to be defended against objections like those sketched above. A second possibility is that we need the ‘messier’ theory. If so, we must ask what shape that theory ought to take, and how lofty should be the ambitions of those who construct it. We need to know how much order can be imposed, at the theoretical level, on the ‘disorderly set of considerations’ with which we are confronted (for one answer, see Tadros 2016, 159–172). As the criminal law’s scope in many jurisdictions continues to expand at a dizzying pace, these remain the most urgent questions facing today’s philosophers of criminal law.