The comparative study of legislation from two different legal systems is difficult. Further complications are encountered when the legislation in question comes from such different legal systems as common law and continental law. The author analyzes and compares the regulations of the English Merchant Shipping Act from 1995 with the Polish maritime code and the four main marine acts: on Polish marine areas and maritime administration; on maritime safety; on the prevention of marine pollution by vessels; on employment on merchant vessels. These acts are discussed from the position of the responsibility of the merchant vessel captain who violates them. One of the basic features of the English criminal code is that every punishable act is regarded in a strict sense as a crime. English law does not recognize the division into crimes and offences. The classification of all punishable acts as crimes in the strict sense means that all of them fall within the jurisdiction of the common criminal courts.The author analyzes crimes against vessel nationality, the flag, and the credibility of documents. Violations in regulations regarding safety are also addressed.