At 28, the appointment made Guanzon the youngest mayor in the Philippines.[4] She was appointed after several other candidates had declined to be mayor of Cadiz, fearing violence from local strongman Armando Gustilo,[11] who had played a key role in the Escalante massacre just a few months earlier, in September 1985.[4][12] Due to the constant harassment by Gustilo and his supporters, she had to carry firearms for defense, even during social occasions and public events.[4]
The provisional government soon proposed a new constitution, and its ratification in February 1986 meant that appointed local government posts would be replaced by elected officials from the 1988 Philippine elections. Guanzon ran and then won the seat she had been appointed to, as Cadiz mayor.[13]
She served as mayor until the end of her term in 1992.[13]
University of the Philippines College of Law, Diliman
On March 8, 2013, she was appointed commissioner to the Commission on Audit (COA),[14] promising "to give priority to gender and development" upon her appointment.[15] The COA commissioners at the time were Chairperson Ma. Gracia M. Pulido Tan and Commissioner Heidi L. Mendoza, and Guanzon's filling of the third seat made the COA an all-women-led agency.[14]
Commission on Elections
On April 28, 2015, Guanzon was named a commissioner to the Commission on Elections (COMELEC) for a seven-year term, lasting until February 2022.
During the 2022 Philippine presidential election, Guanzon notably presided over the disqualification cases filed against presidential candidate Bongbong Marcos that were raffled to the COMELEC First division. Days before retirement, Guanzon publicly named fellow commissioner Aimee Ferolino as "the one delaying the decision in favor of Marcos" before leaving the post. Guanzon claimed that Ferolino was purposely delaying her resolution regarding the disqualification case for Guanzon's vote to not be counted because of pending retirement. Guanzon publicly expressed dismay against Ferolino, and mentioned that an "influential senator" was also interfering with the case. Meanwhile, Ferolino lambasted Guanzon for "mind conditioning" the public against her and reiterated that "she needed more time".[16] Eventually, the First Division decided to junk the petition in favor of Marcos after Guanzon's retirement.[17]
On June 14, 2022, all of P3PWD's nominees withdrew and a new set of nominees was named with Guanzon as its first nominee. The Commission on Elections approved the substitution and Guanzon took oath on June 23. Guanzon's assumption of her position as P3PWD representative was halted by a temporary restraining order by the Supreme Court taking action on the petition of Ronald and Ducielle Marie Cardema of the Duterte Youth.[20][21] In 2024, the Supreme Court barred Guanzon from taking her congressional office by nullifying her nomination, citing grave abuse of discretion by COMELEC in approving her substitution past the designated deadline.[22]
Publications
Guanzon's published works include Issues and Problems in the Enforcement of the Anti-Violence Against Women and Their Children Act of 2004, Philippine Law Journal (Dec 2008); Constitutional Challenges to the Anti-Violence Against Women and Their Children Act of 2004, Journal of the Integrated Bar of the Philippines (March 2009); The Anti-Trafficking in Persons Act: Issues and Problems, Journal of the Integrated Bar of the Philippines; and Legal and Conceptual Framework of Battered Woman Syndrome as a Defense, Philippine Law Journal (Vol. 86, No. 1 December 2011).
The U.P. Law Center also published Guanzon's book, The Anti-Sexual Harassment Act Notes and Cases in 2014. Guanzon is currently writing textbooks on The Local Government Code for the University of the Philippines and The Auditing Code of the Philippines Casebook.
