On September 22, 1994, Peralta was appointed judge of the Regional Trial Court, Branch 95, Quezon City, which was designated as Special Criminal Court on Heinous Crimes and, later, Drugs Cases,[5] then named to the Sandiganbayan in 2002 by President Gloria Macapagal-Arroyo.[4] He was designated presiding justice of the Sandiganbayan in March 2008,[7] and served in that capacity until his appointment to the Supreme Court. Peralta is the chairperson of the High Court's Committee on the Revision of the Benchbook on the Application, Computation, and Graduation of Penalties. He previously sat as a member of the House of Representative Electoral Tribunal (HET).[5] Peralta was the chairman of the 2014 Philippine Bar Examination committee.[1][8]
In December 2020, he announced that he would retire on March 27, 2021; a year earlier than his required mandatory retirement, of which he was succeeded as chief justice by Alexander Gesmundo on April 5, 2021.[9]
Peralta was the recipient of several commendations, two of which were the Special Centennial Awards in the Field of Criminal Law, given by the Integrated Bar of the Philippines and the Supreme Court during its centennial celebration on June 6, 2001, and the Judicial Excellence Awards 2002 (Chief Justice Ramon Avanceña Award for Outstanding Regional Trial Court Judge).[5] In recognition of his vast contribution in the field of law, he was also the recipient of the Outstanding Thomasian Alumni Awards for Law (TOTAL Awardee in Law/Justice) on August 2, 2008, which was the highest award bestowed by the University of Santo Tomas to an alumnus.[10]
