If we are talking about Blue Cards, we need to mention The International Convention on Civil Liability, often called the Civil Liability Convention (CLC). CLC is an international maritime convention administered by the International Maritime Organization to ensure adequate compensation for sea pollution by tankers.
The CLC Protocol outlines that the owner of a ship will be held liable for any pollution damage caused by oil that has leaked or been discharged from the ship. As a result of an incident, except as provided in paragraphs 2 and 3 of this Convention, the owners are to be punished.
The main objective of the Blue Card and CLC is to prevent oil spills, which can be caused by oil leaks, residual oil spills from tanker accidents. These spills can have a detrimental impact on the marine ecosystem. CLC aims to make it easy for insurance companies to provide compensation for damages caused by oil spills. We can see the intersection of the Blue Card and CLC here.