I consider the ways in which the courts use a variety of existing powers to determine the scope of criminal offences, on a prospective basis, through declarations as to the limits or extent of the law. I argue that the courts should be emboldened to build on these powers through greater openness to the circumstances in which declarations may be issued. In particular, courts should be more open to actions for declarations as to the scope of criminal offences brought by a broader range of third parties, such as third sector organisations devoted to exposing wrongdoing.