This article reflects upon key challenges that ecology as a field of science has brought to modern environmental law as it operates within civil law systems. An example from European water management regulation elucidates how the traditional perception of judicial decision-making as deductive reasoning does not match the current reality because factual and normative premises are no longer as distinct as presumed. A novel way of formulating judicial decisions is accordingly presented: legal ecology – which aims to provide one answer to the search for more mature environmental methodologies. Legal ecology is based on the writings of the late Ronald Dworkin and especially of Robert Alexy, whose concept of principles as optimization requirements is adapted to fulfill the execution of the aim-setting sections frequently used in environmental regulation. Adjudication with legal ecology is understood to be rooted in normative sources but to be more transparent, open to scrutiny and to invite more evolved argumentative development than is currently the practice in civil law environmental adjudication. As such, the suggested approach might also benefit argumentation in the sphere of human rights and the environment in general – or any other field where aims ought to be balanced or value choice made visibile without compromising the requirements of legal certainty.