Justice Isagani A. Cruz was born on October 11, 1924, to Vicente G. Cruz and Aurora Anzures, in Sampaloc, Manila.

Studied at the Legarda Elementary School, Mapa High School, the University of the Philippines and the Manuel Luis Quezon University [MLQU] School of Law, where he graduated cum laude in 1951, and later placed in the bar examinations conducted in the same year with a grade of 90.15%.

Conferred the Degree of Doctor of Laws (Honoris Causa) by the Manuel L. Quezon University on April 16, 2004.

He served as an Associate Justice of the Supreme Court from 1986 to 1994, and was successively Member and Chairman of the House of Representatives Electoral Tribunal, Chairman of the Senate Electoral Tribunal, Chairman of the First Division of the Supreme Court, and Senior Associate Justice at the time of his retirement in 1994. Two of his landmark decisions were on the notable case of Javier v. Comelec (1986), where Evello Javier, a rival of Marcos’ KBL party member Arturo Pacificador, in the Batasan polls in May 1984 in Antique, was gunned down in an ambush. The Court ruled in favor of Javier. The other decision was on the brutal case of People v. Carmina (1991) qualifying it as a murder.

He was also the legal consultant to various congressional delegations to Denmark, Japan, South Korea, Cambodia, Australia, Indonesia, and the Philippine panel that negotiated the commercial treaty with Japan.

Justice Isagani Cruz also served as the Chairman of the Code Commission from 1966 to 1972, when he resigned to become a Partner in the Laurel Law Offices, where he specialized in Constitutional Law and International Law.

He also became the Dean of the Lyceum School of Law from 1962 to 1968, and of the College of Law of the University of Perpetual Help Dalta System from 1994 to 2009. He holds the Jose P. Laurel Chair on Constitutional Law in the Lyceum.

He taught as Law Professor [Political Law Review, Political Law, Constitutional Law, Public International Law Administrative Law, the Law of Public Officers and Election Law] and Bar Reviewer in the University of the Philippines Law Center, the Ateneo de Manila, San Beda College, the University of the East, Far Eastern University, University of Santo Tomas, University of Manila, San Sebastian College, Adamson University, University of Perpetual Help and other law colleges in Metro Manila from 1952 until his retirement in 2009.

He has authored multiple books such as Philippine Political Law, Constitutional Law, International Law, International Law Reviewer, Co-Authored Decisions and Dissents, Separate Opinion, Res Gestae: A Brief History of the Supreme Court, Correct Choice of Words, Idiomatic Expressions, Fundamentals of English Grammar and Pepito : Speaker of the House, The Public Life of Jose B. Laurel, Jr. and Wrote a week-end column, Separate Opinion, in the Philippine Daily Inquirer from 1995 to 2010.

He was chosen as Outstanding Manilan for Law in 1995, awarded the Jorge C. Bocobo Lecturer of the U.P. Law Center in 1997, Thomas More Lecturer of the UST, and 50th Anniversary Year Lecturer of the MLQEI and received various awards from, among others, the Supreme Court, the Integrated Bar of the Philippines, the Senate and House of Representatives Electoral Tribunals, the Supreme Court Lawyers Association, San Beda College, the MLQU Alumni Association, the UST Faculty of Arts and Letters, the Far Eastern University, the Mapa High School Alumni Association and the National Centennial Commission.

He is married to the former Salvacion Lopez, with whom he has six children – Cesar, Claro, Celso, Carlo, Isagani. Jr., and Cynthia.