Frameworks of environmental regulations are fundamental yet problematic factors in achieving climate mitigation and adaptation policy goals. Recent theoretical arguments claim the value of general legal frameworks to enable experimentation and contextual adaptation of policies. However, empirical research regarding the effects of both general and specific norms in the practice of urban intervention remains limited. In this article we empirically discern how city governments deal with the tension between control and flexibility in the implementation of urban climate change goals. We argue that policies of adaptation/mitigation face two types of implementation problems: non-adaptive implementation and non-implementation. The first stems from an excessively constraining use of rules, while the second derives from a too general and undefined regulatory framework. Analysing two empirical cases in Amsterdam, Netherlands and Boston, MA, USA, we conclude that there are three elements that affect the way actors deal with these deficits: the level of scale at which regulations are established, the degree of land ownership which provides margin of manoeuvre to public authorities, and the sense of political urgency behind mitigation and adaptation