Torture is one of the most serious violations of fundamental human rights. Torture not only destroys the bodies and minds of individuals and their communities, but also undermines the rule of law and democratic institutions in civil society. This chapter addresses one of the most critical factors in torture prevention, accountability, and redress – effective investigation and documentation. Ending impunity for torture and ill-treatment requires effective legal investigation and documentation practices. In addition, effective forensic medical investigation and documentation of torture and ill-treatment often provides one of the most powerful forms of material evidence in corroborating a victim’s allegations of abusive treatment. This chapter reviews the development of international standards for the effective investigation and documentation of torture and ill-treatment known as the Istanbul Protocol, practical application of Istanbul Protocol standards, and examines future directions for Istanbul Protocol implementation.