Lacson chaired a Senate committee investigation into the fatal hazing of law student Horacio "Atio" Castillo III in September 2017. The probe found indications of a cover-up attempt via Facebook chat by Aegis Jvris fraternity, the organization Castillo sought to join. The probe resulted in Senate Bill 1662, which updated the existing Anti-Hazing Act of 1995 by imposing heavier penalties on hazing. The bill passed third and final reading in the Senate on February 12, 2018. It also passed the bicameral conference committee on February 28, 2018. The bill finally became a law after President Rodrigo Duterte signed it on June 29, 2018.