The problem of parasitism is often used to justify union safety agreements. A classic study on the problem of parasitism is presented in Mancur Olson`s 1965 work, The Logic of Collective Action.  In labour relations, there is the problem of parasitists, because the cost of organizing a union and negotiating a contract with the employer can be very high, and because employers will find it too expensive to introduce multiple pay and benefit scales, some or all non-union members may find that the contract also benefits them.  EU security agreements are explicitly mentioned in the labour laws of many countries. They are heavily regulated by laws and court decisions in the United States and, to a lesser extent, in the United Kingdom.  In Canada, the legal status of the union security agreement varies from province to province and at the federal level, with some provinces allowing it but not claiming it, but the majority of provinces (and the federal government) required it when the union required it.  There are different types of union security agreements. Among the most frequent, in February 2015, the Republican governor of Illinois, Bruce Rauner, filed a complaint claiming that fair sharing agreements were unconstitutional and a violation of the First Amendment`s right to freedom of expression. In August 2007, some 85,000 internally displaced persons and refugees, united Nations-assisted persons have returned under the Joint Plan: 8 It is estimated that 45,355 displaced persons returned to their homes in 20079, but the IDMC indicates that the estimated number of internally displaced persons rose to 5,800,000 10 in 2007.
However, this does not indicate that no effort has been made to return internally displaced persons. Between 23 January and the beginning of February 2007, some 747 displaced persons returned to their homes in eight convoys. These returnees are among an estimated 15,000 internally displaced persons who participated in UNHCR`s return under a return agreement signed last year by the World Organization, the Government of Sudan`s National Unity and the Government of South Sudan.11 Nevertheless, humanitarian assistance and fragile security have hampered the return of displaced persons within their communities. Since the beginning of 2007, up to 160,000 people have been displaced in Darfur.12 A union security contract is a conventional contract that is generally part of a union collective agreement in which employers and a union agree on the extent to which the union can compel workers to join the union and/or whether the employer will receive dues, royalties and evaluations on behalf of the union.  This agreement is a positive step in the implementation of the peace agreement signed in August 2015. Sudan`s defence minister and the head of the negotiating team said the integration of SPLA N fighters would make “the army more coherent, stronger and ready to deal with all threats to the security of the country of origin.” By the end of the year, more than 500,000 spontaneous returns of displaced persons and refugees had taken place in Sudan.3 IDMC statistics indicate that internally displaced persons have not been resettled in their communities, as estimated internally displaced persons have not changed for 2006.