“Marine plastic litter can already be controlled through the United Nations Convention on the Law of the Sea (UNCLOS); the London Convention; the MARPOL Convention; the Basel Convention; Customary Law, and many other regional agreements.
Article 194 of UNCLOS, for instance, requires states to ‘prevent, reduce and control pollution of the marine environment from any source.
Measures shall include, inter alia, those designed to minimize to the fullest possible extent… the release of toxic, harmful or noxious substances, especially those which are persistent, from land-based sources… [and] shall include those necessary to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened or endangered species and other forms of marine life.'” http://www.bbc.co.uk/news/science-environment-43115486
If only the legal profession was as persistent.