Obviously pollution hampers badly to prosper and develop the economy of any nation. This thesis explores the applications of existing laws to control marine pollution specifically in Karachi Harbour/its adjoining & generally in the coastal areas of the country and the difficulties faced in application of existing laws of marine pollution as well as Land Based Sources of Marine Pollution in national waters. Environmental degradation of Karachi & its coastal area is a long standing issue and pollution created by a number of sources is the major contributing factor. It identifies the sources and effects of LBSMP in addition to the problems and associated issues in controlling marine pollution. Amongst all, the deteriorating environment at Karachi Harbour warrants immediate corrective actions in order to curtail further destruction by this menace. Many steps both at Governmental as well as at private level have been taken however, improvement is much awaited that there is no shortage of laws on the pollution control but accomplishment of the same by all concerned agencies and cooperation by public in true letter and spirit is a dream. The prevailing environment cannot be improved without enforcement of existing laws in their true perspective by removing all obstacles and difficulties with creating strong political will, a dire need of time. While investigating major issues of Karachi Harbour & its surrounding coastal areas has been studied critically to found actual facts and figures on pollution related activities/problems causing environmental degradation. A close analysis of the existing laws and many conventions/ has been carried out for correct understanding as non-implementation of laws is held responsible of current alarming situation. It is envisaged that performance based regulation is best suited for the purpose of regulating marine pollution. As per the Global findings 80% of marine pollution instigates from land-based sources and it is naturally trans-boundaries. Many legal and policy based initiatives at international level have been taken to incorporate and to manage the principles to establish international regimes to control the environment of marine as of Land Based Sources of Marine Pollution. However, they have yet not been implemented. This analysis gives an unambiguous and broad picture for correct understanding of the major issues related to the Marine Pollution in Karachi Harbour & its adjoining coastal areas and implementation of existing laws for its mitigation in a true letter and spirit as merits.