The global sulphur cap, introduced by the International Maritime Organization (IMO) and decided to be implemented by January 1st, 2020, sets the new sulphur limit to 0.5% not only in coastal areas, but in the high seas as well. The effective enforcement of this measure will ensure a level playing field for all operators in the shipping industry. The challenges expected to arise from this regulation and the available or potential enforcement schemes for the Emissions Control Areas (ECA) zones and the high seas are addressed in this paper. Different alternatives of the penalty policy that may discourage non compliance are analyzed. A model that calculates the profits from non compliance in the high seas is developed to help determine the level of fines that could be imposed in case of violation.