He was chair of Workshop on Administration of Justice, Multi-Sectoral Conference convened to discuss the first 100-day and first 1,000-day programs of President Fidel Ramos, held on June 13, 1992, and on October 17, 1992, respectively.

He was also the former president of Philippine-Finland Association and RCM Eyebank Foundation Inc. Panganiban also writes columns for the Philippine Daily Inquirer and has worked as a consultant and director of various businesses and organizations.

Panganiban was the chairperson of the Supreme Court Third Division and the House of Representatives Electoral Tribunal (HRET), as well as of seven SC committees involved mainly in judicial reforms.

Described by Justice Antonio Carpio as “undoubtedly the most prolific writer of the Court” he penned more than 1,000 full-length decisions and ten books plus several thousand minute resolutions disposing of controversies.

These include the Cocofed case, in which the court gave the Presidential Commission on Good Government the right to vote sequestered United Coconut Planters Bank shares, which had been acquired through coco levy funds.

In his book Reforming the Judiciary, Panganiban recounted that on the morning of January 20, 2001, militants had threatened to march toward Don Chino Roces (Mendiola) Bridge, where Estrada supporters were encamped, unless he resigned.

These led Panganiban to conclude that "the only way to avert violence, chaos and bloodshed and to save our democratic system from collapse was to have Mrs. Arroyo sworn in as Acting President."

Panganiban was named Supreme Court Chief Justice on December 20, 2005, by President Gloria Macapagal Arroyo after Hilario Davide Jr. retired at age 70.

As Chief Justice, Panganiban drew controversy for his remarks made in June 2006 regarding the 1998 decision of the Supreme Court, in which he participated, affirming the death penalty imposed on Leo Echegaray.

Panganiban, whose anti-death penalty views are well known, suggested that the Supreme Court may have committed "a judicial error" in executing Echegaray, as not all of the qualifying circumstances needed to promulgate a death conviction were actually established.

[7] His remarks, coming at the heels of the passage by Congress of a law abolishing the death penalty, were criticized by death-penalty advocates and some newspaper editorials.

...a principled and visionary leader by example; a prolific writer of the Supreme Court, bar none; a renaissance man and a nobly-souled and gifted jurist; a much sought-after speaker; a recipient of over 250 awards and citations from national and international entities and organizations, including several honorary doctoral degrees; an eminent lawyer, law professor, Catholic lay worker, civic leader and businessman; a scholar imbued with mental dexterity; and, an exemplary family man.