 This view may move too quickly to invoke consequentialist considerations. Even if our ability to discern proportionality constraints is crude in absolute terms, comparative proportionality may leave relatively little leeway with regard to what punishments are morally defensible in a given jurisdiction (Robinson 2003; von Hirsch &amp; Ashworth 2005: 180–185; von Hirsch 2011: 212; and section 2 of the supplementary document  Challenges to the Notion of Retributive Proportionality).  Nonetheless, insofar as the constraints of proportionality seem inherently vague, retributivists may have to make some sort of peace with the thesis of limiting retributivism.