Obligation to use the best available technology (BAT) in the protection of the environment is envisaged in many international treaties. It is not only legal, but also moral obligation. Treaties concluded under the auspices of the International Maritime Organization (IMO) that aim at the protection of the environment and the prevention of pollution from ships, enshrine the precautionary principle which encompasses the obligation to use the best available technology. Many IMO treaties consider technological development, some of them even drive it, however, not all standards are based on the best and the newest solutions. The discussion at the IMO’s Marine Environment Protection Committee regarding the energy efficiency design index demonstrates the impact of political and economic interests on the text of adopted standards. The Initial IMO strategy on the reduction of greenhouse gas emissions from ships identifies levels of ambitions consistent with the Paris Agreement. In the shipping industry this will be achieved, if the adopted standards were based on the best available technology.