sentences:  In 2001, Attaran acted as an advisor on patent and trade law to Brazil's Ministry of Health, to defend against a legal challenge the United States brought at the World Trade Organization, which sought to force Brazil to amend its patent laws and prohibit the affordable, generic versions of HIV/AIDS medicines on which the health ministry depended.Attaran and his colleague Paul Champ developed a legal strategy involving a retaliatory challenge to US patent laws.The United States withdrew its case under public pressure and Brazil continued using generic HIV/AIDS medicines for its population.