The Influence of International Law on the International Movement of Persons

Many migration theories identify ‘the law’ as a significant constraint on the international movement of persons. While this constraint often operates through national migration legislation, this study examines the influence of international law in shaping contemporary patterns in the international movement of persons at the macro level. The analysis begins with an examination of the long-established power of a State to regulate cross-border movement of persons as an inherent attribute of State sovereignty, together with the accepted limitations on a State’s power to control entry and exit. Yet, international law reaches well beyond the movement of people across borders. The development of international human rights law has been a key constraint on state action in the United Nations era by also regulating the treatment of migrants within a State’s borders. The study considers how international law has responded to current migration issues, including: protection of migrant women and children; suppression of smuggling and trafficking of people; labour migration; and environmental migration. As in other areas of international society, there has been a proliferation of institutions through which international migration law is made and enforced. The most prominent among them are the United Nations High Commissioner for Refugees (UNHCR) and the International Organization for Migration (IOM), but the establishment of other entities with overlapping mandates has given rise to calls for a new international migration regime based on streamlined institutional arrangements. The study concludes that international law is an imperfect framework for regulating the international movement of persons because it has developed in a piecemeal fashion over a long time to deal with issues of concern at particular points in human history. Yet, despite its shortfalls, international law and its associated institutions unquestionably play a most important role in constraining and channeling state authority over the international movement of persons

Lessons from introductions of exotic species as a possible information source for managing translocations of birds

It has been previously suggested that the characteristics that are driving the taxonomic homogenisation of the global avifauna, through the extinction of native bird species and the establishment of exotic bird species, are opposite sides of the same coin. One of the most important tools that conservation biologists and wildlife managers have to ameliorate the extinction of a species is to reintroduce populations to stronghold areas from which they have been extirpated or were not previously common. In this paper, we address the question of what the study of exotic bird introductions can tell us to inform the translocation of native species. We review the relative importance of the five factors that have been suggested significantly to influence the successful establishment of non-native species: introduction effort, environmental matching, species’ interactions, species’ life histories, and phylogenetic relatedness. Current evidence suggests that introduction effort will be an important determinant of release, but how many individuals need to be released, and in how many separate release events, is contingent on characteristics of species and environment. The importance of climate matching for introduction success suggests that the success of translocations will depend greatly on the study and amelioration of the problem that caused the initial population decline. This is most problematic in situations where the decline is associated with human-induced climate change. Migratory and sexually selected species may be harder to re-establish, but related species may differ substantially in their likelihood of success. We suggest that further insights into the reintroduction process may be gained particularly by studying species that are experiencing a threat in their native range but which are also being widely released as exotics outside of this range.Phillip Cassey, Tim M. Blackburn, Richard P. Duncan and Julie L. Lockwoo