Mercado was among the councilors who principally proposed ordinances that attempted to counteract the violent incidents that occurred in Caloocan during the early years of the Philippine drug war.
[8][9][10] In October 2014, a warrant of arrest was issued against vice mayor Macario Asistio III and the entire city council, which included Mercado, by Caloocan Regional Trial Court (RTC) judge Dionisio Sison of Branch 125 for the non-payment of a property acquired by the local government in 1996.
[12] In May 2017, Mercado proposed an ordinance that penalizes "professional squatters", or informal settlers who occupy land without consent but have enough income to afford proper housing, which received pushback from the Kalipunan ng Damayang Mahihirap (Kadamay) Kalookan urban poor organization.
[16] In April 2018, Mercado proposed an ordinance alongside PJ Malonzo and Nubla that restricted motorcycle-riding male tandems after a series of shooting incidents perpetrated by motorcycle riders occurred in the city.
[21][20] On February 17, 2021, Mayor Malapitan filed a cyberlibel complaint against Mercado, Malonzo and three other opposition councilors due to their "series of videos" accusing his government of procuring substandard digital tablets for schools.