The United Nations system supported the work of States in developing laws and improving responses to trafficking by law enforcement agencies and the criminal justice system . Many United Nations agencies contributed to the development of national anti-trafficking legislation ( the United Nations Development Programme ( UNDP ) in Argentina and Lesotho and the United Nations Entity for Gender Equality and the Empowerment of Women ( UN-Women ) in Viet Nam ) , to police reform ( UNDP in Bangladesh ) and to the incorporation of human rights principles into judicial decisions on gender-based violence ( inter-agency working groups on gender and human mobility operating under the auspices of the United Nations country team in Argentina ) .