Arroyo participated in the trials of political detainees such as Senator Benigno Aquino, Jr., ABS-CBN Executive Eugenio Lopez, Jr., Cebu politician Sergio Osmeña III, Communist Party of the Philippines founder and University of the Philippines Professor Jose Maria Sison, Senators Jovito Salonga and Eva Kalaw, lawyers Aquilino Pimentel Jr., Renato Tañada, Eduardo Olaguer and many others.