The United Nations Inter-Agency Project on Human Trafficking (UNIAP) maintains a listing of relevant international anti-trafficking laws, as well as the year in which they were passed. You'll also find a list of international protocols and conventions related to slavery, human trafficking and human smuggling. Full text is available for many documents.
UNODC MODEL INTERNATIONAL LAW
The UNODC Model Law against Trafficking in Persons was developed by the United Nations Office on Drugs and Crime (UNODC) in response to the request of the General Assembly to the Secretary-General to promote and assist the efforts of Member States to become party to and implement the United Nations Convention against Transnational Organized Crime and the Protocols thereto. It was developed in particular to assist States in implementing the provisions contained in the Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women and Children, supplementing that Convention.
FEDERAL LAWS (USA)
The United States Department of Justice Civil Rights Division maintains information on U.S. federal laws related to slavery and human trafficking, including the Thirteenth Amendment to the U.S. Constitution and the Victims of Trafficking and Violence Protection Act of 2000 (VTVPA).
STATE LAWS (USA)
Polaris Project's U.S. Policy Program is actively engaged on the state policy front on a national scale. They work to strengthen existing laws, monitor and encourage increased implementation and utilization of current laws, and pass new anti-trafficking legislation, where appropriate and necessary. While the method and level of involvement varies from state to state, Polaris often works in partnership with local advocacy groups and organizations, state and local task forces and coalitions, and grassroots community volunteers to support locally-led anti-trafficking legislative approach. Polaris also tracks and rates laws in each state.
MODEL STATE LAW (USA)
Polaris Project offers State Legislative Advocacy and Resources, including comprehensive model state legislation, as well as summaries and guidelines. Polaris advises state legislators and their legislative staff, and has worked to advance legislation in more than 25 states.