Pien Metaal is a researcher with TNI. She holds a Master of Arts Degree in Political Science and International Relations from University of Amsterdam. She has been a member of the Transnational Institute's Drugs and Democracy team since 2002, though her participation with the team dates further back.

She lived in Latin America for seven years, spending most of that time in Bolivia. During those years, she dedicated most of her time and energy to the drug policy, particularly in relation to coca and cocaine, and worked with local NGOs. She has written numerous articles, and contributed to various books and publications on the topic in recent years.