Having first questioned the novelty of the unilateral/environment debate, this article proceeds to consider two aspects of unilateral behaviour of particular interest today: the "policy-forging" and the "implementation or enforcement" facet of unilateral acts. The first facet deals with the manner in which unilateral acts shape legal outcomes in the environmental context, whilst considerations of the second facet concentrates on how legally required outcomes are avoided, mitigated or re-interpreted by unilateral acts.