2 Some key differences to other forms of ship-source pollution
The enforcement of ship-source pollution more generally is governed by a well-established legal framework at international level, set up by jurisdictional rules of UNCLOS and technical rules established by the IMO, notably the International Convention on the Prevention of Pollution from Ships (MARPOL). However, in comparison to other forms of ship-source pollution, such as oil discharges, the enforcement of air emission standards presents some particularities and specific challenges, which justify a separate legal assessment of this specific matter.
As opposed to oil spills, air emissions do not happen as a result of isolated events or incidents of a one-off nature, but are of a continuous operational nature. Compliance with the rules entails significant costs for ship operators. (1) By operating on non-compliant heavy fuel oil, a medium-sized container ship can save up to 150.000 USD on a return trip through the Northern European SECA. See e.g. 'Sulphur in Marine Fuels', Policy Paper, Danish Shipowners' Association, August 2016. Conversely, there are important gains to be made by rule avoidance and it is technically relatively easy to switch between compliant and non-compliant fuel. This starting point would call for a robust monitoring and enforcement system, including at sea, and sizeable penalties for identified instances of non-compliance. Yet air emissions involve specific challenges in both areas
Unlawful emissions are not as easily detected as oil spills. Even an initial indication of non-compliance requires sophisticated equipment and the eventual verification of a violation is a technically complex operation, requiring specialist expertise and equipment and a considerable amount of time. The continuous character of the violation also means that proof that the rules have been violated at a given moment does not necessarily say much about the extent or duration of the violation.
Even if proof of the (objective) violation is available, the infringement also needs to pass the requirements on (subjective) culpability of the persons concerned. Many persons are involved in the decisions relating to fuel usage and the ones who carry out the operations in practice are not necessarily the ones that benefit from them. The range of liable persons and the level of culpability required for an infringement are regulated at national level, but in most cases some degree of negligence is required. Proving negligence is also complex when it comes to fuel quality requirements. High sulphur contents in the fuel may be due to many different reasons. Documentary evidence is normally not available to demonstrate culpability while proof that compliant fuel has been purchased is normally easy to present. (2) See study prepared by the Swedish Transport Agency, Transportstyrelsen, Rapport: Tillsyn och efterlevnad av de skärpta reglerna för svavelhalt i marint bränsle', Slutrapport, Dnr TSS 2013-2085, juni 2014, at p. 50.
Moreover, the principles for characterizing the violation and addressing the size of penalties for environmental infractions are commonly based on the environmental harm or the level of danger for humans or the environment of the infringement, which is not suitable for air emission violations. The environmental and health risks and threats in this case lie in the collective effects of non-compliance, rather than in an individual infringement. The absence of significant environmental damage in the individual case also means that other liability mechanisms, such as civil liability, is not available for use as a complementary deterrent.
Such particularities place special demands on monitoring and enforcement, both at sea and in ports. Yet the differences between air emissions and other forms of ship-source pollution have not been given much attention in the relevant international rules. The jurisdictional framework for ship-source pollution as laid down in the United Nations Convention on the Law of the Sea (UNCLOS) was drafted at a time when ship-source air pollution was not a matter of significant concern. The convention focuses on marine pollution and neither the rules on 'discharges' nor the specific rules on 'pollution from or through the atmosphere' seem entirely suitable to govern jurisdictional matters relating to ships' air emissions. The technical rules, as laid down in the main body and in Annex VI of MARPOL, do not significantly distinguish the enforcement of air emissions violations from other types of violations regulated in the other annexes. The EU rules on the topic similarly include limited regulation on how non-compliances shall be enforced.