nuclear weapons could actually provide evidence of their "use" as a deterrent force. This logical framework makes sense for existing norms of customary international law, but it becomes problematic in the context of new or emerging customary rules. If a practice is not currently governed by customary international law, then it is illogical to inquire into a state's beliefs about the legality of engaging in or abstaining from that practice, i.e., to ask whether it believed that its practice was in compliance with a law that does not yet exist. This paradox may be resolved to some extent by the idea of "crystallization" of customary international law, in which practice and legal obligation evolve jointly and eventually ripen into law. Under one model, this process occurs in three stages: first, some States engage in a given practice for reasons other than a sense of legal obligation (e.g. political expediency, economic gain, courtesy, etc.); next, States reinforce the practice by engaging in it or making claims based upon it, creating loops of reciprocity and reliance based on expectations that the practice will continue; finally, as these relationships expand in number and complexity, they eventually harden into a general rule. In this final stage, as more States become aware of the conduct and actively participate or at least passively acquiesce to the practice, the States' actions begin to be undergirded by a belief that they are complying with an emerging customary rule. Notes and references Latin legal terminology International law