The growing quantity of plastic waste in the marine environment including abandoned, lost or otherwise discarded fishing gear (ALDFG) is a global problem. A particular feature of ALDFG is the potential of some gears to carry on fishing for many months or even years. The study examines legal responses to ALDFG in the context of marine fisheries. After discussing the nature of the problem of ALDFG and some of the reasons why fishing gear is abandoned, lost, or otherwise discarded, the study examines the response of the international community to ALDFG. A key finding is that ALDFG is at the same time, a fishing issue, a navigation problem (of vessel source pollution) and an environmental problem with the resulting involvement of FAO, IMO and UNEP as well as the UN General Assembly. After examining potential legal approaches to the problem, the study then describes the basic legal and institutional arrangements in four case study jurisdictions that have adopted legal measures to address ALDFG, namely Australia, the European Union and its Member States, Norway and the USA finding once again the tripartite responsibility of fisheries, navigation and environment ministries/agencies. The inter-sectoral nature of ALDFG suggests the need for a collaborative and coordinated approach. While not all of the case study jurisdictions make use of all ten of the individual legal measures identified, the case studies also clearly show that ALDFG is a problem that is susceptible to a legal response at the national or regional level including through the use of extended producer responsibility schemes, various reporting requirements and gear standards. Legal tools to address the problem of ALDFG clearly exist. The extent to which some, or all, of them are necessary or appropriate in a given context at national, regional or global level is not ultimately a legal question but a political one.