She finished studies in the National Institute and the
University of Panama, where she obtained her bachelor's degree with honours in Agronomy Engineering. She also holds post-graduate studies in education. She served as Mayor of
San Miguelito, congresswoman, and
President of the National Assembly (1994–1995) with the
Democratic Revolutionary Party (PRD). When a male legislator once interrupted her to say that women should be at home with her children, she punched him and yelled, "Respect women!" but supported his initiative to abolish the armed forces. In 1996, Herrera supported President
Ernesto Pérez Balladares's bill to grant amnesty to 950 former officials of military ruler
Manuel Noriega, dismissing criticism of the bill as an attempt by fractured opposition parties to find a new common cause. In the same year, she spoke out against an attempt to revive
capital punishment, after a wave of murders of bus and taxi drivers. Herrera was elected as President of the National Assembly in 1994, the first woman to hold the post. She also served as chairwoman of the Parliamentary Trade Commission in 1998, calling on pharmaceutical companies to rein in rising prices or face government price controls. In December 2000, human remains were discovered at a Panamanian National Guard base, incorrectly believed to be those of
Jesús Héctor Gallego Herrera, a priest murdered during the
Omar Torrijos dictatorship. Moscoso appointed a
truth commission to investigate the site and those at other bases. The commission faced opposition from the PRD-controlled National Assembly, who slashed its funding, and from Herrera, who threatened to seek legal action against the president for its creation. The commission ultimately reported on 110 of the 148 cases it examined, concluding that the Noriega government had engaged in "torture [and] cruel,
inhuman, and degrading treatment", and recommending further exhumation and investigation. In 2001, Herrera led opposition to President
Mireya Moscoso's appointment of former Interior Minister
Winston Spadafora to the Supreme Court. The following year, National Assembly member
Carlos Afu, who was being expelled from the PRD for his vote in support of Spadafora's nomination, accused the party of taking bribes
en masse under Herrera's leadership from the San Lorenzo consortium, a government contractor. During the presidency of
Martin Torrijos (2004–09), Herrera served as Minister of Housing. == 2009 presidential election ==