Particular social group (PSG) is one of five categories that may be used to claim refugee status according to two key United Nations documents: the 1951 Convention relating to the Status of Refugees and the 1967 Protocol relating to the Status of Refugees. The other four categories are race, religion, nationality, and political opinion. As the most ambiguous and open-ended of the categories, the PSG category has been the subject of considerable debate and controversy in refugee law. Note that just as with the other four categories, membership in a PSG is not sufficient grounds for being granted refugee status. Rather, to be granted refugee status, one must both demonstrate membership in one of the five categories (race, religion, nationality, particular political opinion, and particular social group) and a nexus between that membership and persecution one is facing or risks facing.A particular social group is a group of persons who share a common characteristic other than their risk of being persecuted, or who are perceived as a group by society. The characteristic will often be one which is innate, unchangeable, or which is otherwise fundamental to identity, conscience or the exercise of one’s human rights. Particular social group (PSG) is one of five categories that may be used to claim refugee status according to two key United Nations documents: the 1951 Convention relating to the Status of Refugees and the 1967 Protocol relating to the Status of Refugees. The other four categories are race, religion, nationality, and political opinion. As the most ambiguous and open-ended of the categories, the PSG category has been the subject of considerable debate and controversy in refugee law. Note that just as with the other four categories, membership in a PSG is not sufficient grounds for being granted refugee status. Rather, to be granted refugee status, one must both demonstrate membership in one of the five categories (race, religion, nationality, particular political opinion, and particular social group) and a nexus between that membership and persecution one is facing or risks facing. PSG determination is part of the general refugee determination process in most countries that are signatories to the 1951 Convention. In particular, these decisions are made by the immigration bureaucracies, immigration courts, and the general courts (to which immigration decisions may need to be appealed). Past decisions create guidelines and precedents for future decisions in the same country. In general, decisions in one country do not create precedents for decisions in other countries, but there is some influence through the influence on periodically updated UNHCR guidelines and through lawyers' use of these cases. Two particularly seminal decisions influencing PSG determination worldwide have been Matter of Acosta (1985, United States), and Ward (1993, Canada). Examples of PSGs identified in various countries include women (and various subsets thereof), homosexuals and others with non-mainstream sexual orientations, specific families, and the poor. In 2002, the United Nations High Commission for Refugees (UNHCR) published updated guidance for the interpretation of the PSG category.