A/HRC/14/30/Add.2 Organization for Migration (IOM) with a view to conducting the above-mentioned study; (d) Take all necessary steps to protect all migrant workers and their families, with special attention to the accountability of abusive employers, and ensure that labour contracts are inclusive and written in a language that the migrant can understand, contain detailed employment conditions including the employee’s right to terminate the contract under specified conditions and contain all other relevant information (workplace, duration, salary, working hours and the conditions of stay, including residency documents and work permit, suitable and sanitary living quarters, adequate food and medical services and information on where to find assistance in case of problems); (e) Avail itself of the expertise of the United Nations, including the Statistics Division of the Secretariat and the United Nations Country Team to develop appropriate national data collection and analysis methodologies that will generate comparable data on the international migrant population, tracking abusive employers of migrant workers and reporting abuses and irregularities in connection with the employment of migrant workers; (f) Ensure that its legislation prohibits the retention of identity documents by employers or recruitment agents; prohibits all systems of forced sponsorship of migrants, which are designed to ensure control over the migrant throughout the period of residence, and avoids linking the residence permit of a migrant worker to a single employer as measures to prevent exploitation and forced labour; (g) Establish effective and accessible channels which allow all migrant workers to lodge complaints of violations of their rights without fear of retaliation on the grounds that they may be in an irregular situation; 107. In relation to the protection and assistance of victims of trafficking in persons, the Special Rapporteur recommends that the Government: (a) Take all necessary measures to guarantee the effective protection of witnesses and victims of trafficking in persons sale of children, contemporary forms of slavery and forced labour as a key element for the successful investigation and prosecution of perpetrators; (b) Incorporate into national policies, plans and programmes, and effectively implement the Recommended Principles and Guidelines on Human Rights and Human Trafficking;23 (c) Enhance the protection of and assistance to victims of trafficking in persons, in cooperation with international and regional organizations, nongovernmental organizations, the private sector and other stakeholders; (d) Take all necessary steps to prevent multiple discrimination and revictimization of trafficked persons, including prohibiting the labelling of returned trafficked victims as “returned prostitutes”; (e) Ensure that appropriate training is given to law enforcement officials and adopt the necessary measures to ensure the implementation by law enforcement officials of legal provisions guaranteeing that assistance and protection provided to victims are not dependent on their cooperation in testifying against the traffickers; 23 GE.10-12102 E/2002/68/Add.1. 21