Born on January 6, 1952 in Bayombong, Nueva Vizcaya to Judge Quirino R. Sadang and Adoracion L. Cabarroguis, Justice Melchor Quirino C. Sadang completed his elementary education, with honors, and secondary education, as class valedictorian, from St. Mary’s University in Bayombong, Nueva Vizcaya. Thereafter, he earned his Bachelor of Arts (Political Science) in 1972 and Bachelor of Laws in 1976, both from the University of the Philippines in Diliman, Quezon City. He passed the 1976 Bar Examinations with a rating of 84.7% and was conferred Career Executive Service Officer (CESO) eligibility in 1994.
He began his career with stints in the Board of Investments, as legal officer, and the Office of the Solicitor General, as trial attorney. In 1979, he joined the
Cruz Valdez Law Office and later did corporate work for the Fortune group of companies. He returned to government service in 1986, having been appointed
State Prosecutor I in the Department of Justice, and was successively promoted to State Prosecutor Il, Senior State Prosecutor, and Regional State Prosecutor for Region III. While serving as a prosecutor, he was appointed by President Fidel V. Ramos in 1991 as Member of the Government of the Republic of the Philippines Panel that negotiated with the Rebolusyonaryong Alyansang Makabayan (RAM).
In 1994, he put up his own law office and engaged in private practice. He also taught at the College of Law, University of the East.
On July 17, 2000, he was appointed to the bench as Presiding Judge of the Regional Trial Court, Branch 17, Cavite City. He had been a nominee for Judicial Excellence.
On March 22, 2011, he was promoted as Associate Justice of the Court of Appeals where he served for 6 years until he retired on January 6, 2017.
While in retirement, he wrote and published a book on his faith entitled, “My Catholic Faith: A Layman’s Apologia”. In February 2023, he was named as member of a 5-Man Ad Hoc Committee tasked to advise President Ferdinand Romualdez Marcos, Jr. on the courtesy resignations of PNP officers. On April 18, 2024, he was appointed Chairman of the Presidential Commission on Good Government (PCGG).
While serving as prosecutor and RTC Judge, he was elected as Assistant Secretary General, National Prosecutors League of the Philippines, and as Vice-President for Research and Judicial Education, Philippine Judges Association. He had also served as member of the Board of Directors of the Upsilon Sigma Phi Alumni Association.
Justice Sadang is happily married to Atty. Mareyca Balasbas-Sadang with whom he has four (4) children: Carlo, Ronaldo, married to Joan Vel dela Cruz-Sadang, Enrico, married to Jimmy Rose Panzo-Sadang, and Mariel. He has three grandchildren, Alfonso, Antonio and Alfredo.