The PCG is likewise mandated to conduct MARITIME LAW ENFORCEMENT (MARLEN) and implement laws on fisheries (and poaching), immigration, tariff and customs, forestry, firearms and explosives, human trafficking, dangerous drugs and controlled chemicals, and to implement the revised penal code and all other applicable laws within the country’s maritime jurisdiction and battle transnational crimes. 

The PCG is authorized to board and inspect all watercrafts suspected to be involved in or used in illegal trade. PCG personnel are also deemed agents of BFAR, Immigration, Customs, DENR, PDEA, and INTERPOL in the performance of its MARLEN function.

As a maritime organization  under RA 9993 , it is deputized by 21 government agencies to perform maritime law enforcement functions directed towards the suppression of piracy, smuggling, poaching, illegal fishing, illegal entry, human smuggling, illegal logging, drug trafficking, gun running and terrorist activities.