The present study analyses the legal requirements concerning discharge of water from ships, a matter that is characterized by a considerable degree of complexity. This complexity results, inter alia, from the highly technical nature of the applicable norms, but also from the fact that the relevant rules and principles are prescribed on different levels of law, namely public international law, European Union law and domestic law. Taking into account that the individual legal instruments that are codified within these sub-systems of law significantly differ in their scopes and regulatory approaches, a risk of norm collisions exists both from a vertical (i.e., between different levels of law) and horizontal (i.e, between different instruments on the same level of law)
perspective. Viewed together with the fragmentary nature of the applicable law, this situation gives rise to legal uncertainties, which, again, may ultimately threaten the lawful and effective
implementation and enforcement of the relevant norms. This study attempts to contribute to
clarifying the existing uncertainties by submitting suggestions as to a harmonized interpretation
and application of the pertinent rules and principles. It does not address the issue of pollution
from ships in general, but focusses on three specific categories of water discharged from ships, namely washwater arising from the operation of exhaust gas cleaning systems (ʻscrubberʼ), ballast water and sewage. The study starts by examining the legal requirements prescribed in
international treaty law as well as the law of the European Union (EU) applicable to each of the three aforementioned categories. Particular attention is devoted to the territorial and substantial scope of the relevant instruments, potential interactions and contradictions between them as well as the rights and duties of States arising therefrom. The study then goes on by analysing the way in which these instruments have been implemented in domestic German law. In this respect, the
main focus is on how Germany has adjusted the international and supranational obligations within the framework of its domestic law.