The legal operationalisation of ecological sustainability concerns all levels of legal control. The ensuring of full biodiversity is an indispensible component of ecological sustainability. At the same time, biodiversity losses continue to be a serious problem in many regions of the world. The international community has responded to this dilemma by strengthening international biodiversity law as well as agreeing upon a particular biodiversity target. The aim is to reduce biodiversity losses at all levels by the year 2010. From a legal point of view this seems unproblematic. When, however, the international legal order is viewed as an overarching control system, composed of several multi-levelled and interacting international and national legal systems (controlling programs), questions on whether the order can actually work for biodi-versity seem inevitable. By applying and developing further environmental law methodology (ELM) the study argues that some fundamental principles of the international legal order are either diminishing or counteracting the possible realisation of ecological sustainabil-ity and the 2010 biodiversity target of halting and reversing the biodiversity loss. This, as will be argued, is due to rule of law and to how the default actually functions in the international legal system. In line with the above, the prime objective of the study is to develop and elaborate a theory framework on which the theory of the significance of the default is based; second, to evaluate and discuss some fundamen-tal principles of the international legal order and international biodiversity law in the light of the theory, and finally to evaluate and discuss the possible realisation of ecological sustainability and the 2010 target. The study’s method is to a certain extent pluralistic, but it is basically an adapted version of ELM.

The thesis is a comparative legal analysis of environmental principles in environmental law. Environmental principles are novel concepts in environmental law and they have a high profile in environmental law scholarship. This high profile is promoted by two factors – the high hopes that environmental law scholars have for environmental principles, and the increasing prevalence of environmental principles in legal systems, particularly in case law. This thesis analyses the latter, mapping doctrinal developments involving environmental principles in two jurisdictions and court systems – the courts of the European Union and the New South Wales Land and Environment Court. This doctrinal mapping has both narrow and broad aims. Narrowly, it identifies the legal roles in fact taken on by environmental principles within legal systems. Broadly, and building on this assessment, it responds to scholarly hopes that environmental principles (can) perform a range of significant roles in environmental law, including solving both environmental problems and legal problems in environmental law scholarship. These hopes are based on assumptions about environmental principles that have methodological weaknesses, including that environmental principles are universal and that they fit pre-existing models of ‘legal principles’ drawn from other areas of legal scholarship. The thesis exposes these methodological problems and concludes that environmental principles are not panaceas for pressing and perceived problems in environmental law. It does this by showing that the legal roles of environmental principles, which are significant in environmental law and its current evolution, can only be understood by closely analysing the legal cultures in which they feature. This is a conclusion for environmental law scholarship generally – while environmental issues and problems may be urgent and often global, legal analysis of the law that applies to those problems requires close engagement with legal systems and cultures, as they are and as they develop.