Introduction: "All persons should, by virtue of their essential humanity, enjoy all human rights. Exceptional distinctions, for example between citizens and non-citizens, can be made only if they serve a legitimate State objective and are proportional to the achievement of that objective. Citizens are persons who have been recognized by a State as having an effective link with it. International law generally leaves to each State the authority to determine who qualifies as a citizen. Citizenship can ordinarily be acquired by being born in the country (known as jus soli or the law of the place), being born to a parent who is a citizen of the country (known as jus sanguinis or the law of blood), naturalization or a combination of these approaches. A non-citizen is a person who has not been recognized as having these effective links to the country where he or she is located. There are different groups of non-citizens, including permanent residents, migrants, refugees, asylum-seekers, victims of trafficking, foreign students, temporary visitors, other kinds of non-immigrants and stateless people. While each of these groups may have rights based on separate legal regimes, the problems faced by most, if not all, non-citizens are very similar. These common concerns affect approximately 175 million individuals worldwide—or 3 per cent of the world?s population. Non-citizens should have freedom from arbitrary killing, inhuman treatment, slavery, arbitrary arrest, unfair trial, invasions of privacy, refoulement, forced labour, child labour and violations of humanitarian law. They also have the right to marry; protection as minors; peaceful association and assembly; equality; freedom of religion and belief; social, cultural and economic rights; labour rights (for example, as to collective bargaining, workers? compensation, healthy and safe working conditions); and consular protection. While all human beings are entitled to equality in dignity and rights, States may narrowly draw distinctions between citizens and non-citizens with respect to political rights explicitly guaranteed to citizens and freedom of movement. For non-citizens, there is, nevertheless, a large gap between the rights that international human rights law guarantees to them and the realities that they face. In many countries, there are institutional and pervasive problems confronting non-citizens. Nearly all categories of non-citizens face official and non-official discrimination. While in some countries there may be legal guarantees of equal treatment and recognition of the importance of non-citizens in achieving economic prosperity, non-citizens face hostile social and practical realities. They experience xenophobia, racism and sexism; language barriers and unfamiliar customs; lack of political representation; difficulty realizing their economic, social and cultural rights—particularly the right to work, the right to education and the right to health care; difficulty obtaining identity documents; and lack of means to challenge violations of their human rights effectively or to have them remedied. Some non-citizens are subjected to arbitrary and often indefinite detention. They may have been traumatized by experiences of persecution or abuse in their countries of origin, but are detained side by side with criminals in prisons, which are frequently overcrowded, unhygienic and dangerous. In addition, detained non-citizens may be denied contact with their families, access to legal assistance and the opportunity to challenge their detention. Official hostility—often expressed in national legislation—has been especially flagrant during periods of war, racial animosity and high unemployment. For example, the situation has worsened since 11 September 2001, as some Governments have detained non-citizens in response to fears of terrorism. The narrow exceptions to the principle of non-discrimination that are permitted by international human rights law do not justify such pervasive violations of non-citizens? rights. The principal objective of this publication is to highlight all the diverse sources of international law and emerging international standards protecting the rights of non-citizens, especially: The relevant provisions of the International Convention on the Elimination of All Forms of Racial Discrimination and other human rights treaties; The general comments, country conclusions and adjudications by the Committee on the Elimination of Racial Discrimination and other treaty bodies; The reports of the United Nations Commission on Human Rights thematic procedures on the human rights of migrants and racism; The relevant work of such other global institutions as the International Labour Organization and the Office of the United Nations High Commissioner for Refugees; and The reports of regional institutions, such as the European Commission against Racism and Intolerance."