Former state Supreme Court Justice Andrew G.T. Moore II, regarded as one of the seminal voices in Delaware corporate law, died Monday at the age of 83.

Moore, whose legal career spanned more than five decades, served 12 years on the state high court, where he wrote landmark decisions in Revlon v. MacAndrews & Forbes Holdings and Aronson v. Lewis, among others. A native of New Orleans, Moore also launched the Tulane Corporate Law Institute conference, and in his later years helped to build out the Wilmington office of Gibbons.

The law firm announced Moore's passing in a press release Thursday.

“He immediately raised the firm's profile in a region that is vital to many of our clients' businesses, added a layer of instant credibility in that market, and worked closely with firm management to broaden and enhance our services there,” Patrick C. Dunican Jr., Gibbons' chairman and managing director, said in a statement. “And beyond Gibbons, he left an indelible legacy for the legal community throughout Delaware.”

Prior to his service on the bench, Moore practiced corporate litigation as a partner at Connolly Bove Lodge & Hutz in Wilmington. He was appointed to serve as a justice by Gov. Pierre S. duPont IV in 1982 and quickly earned a reputation as the court's leading jurist on matters of corporate governance.

Moore's 1986 ruling in Revlon crafted an enduring doctrine requiring that a company's board of directors make a reasonable effort to obtain the highest value for a company when a hostile takeover or change of control is imminent. In Aronson, Moore laid out the test used by Delaware courts to determine whether a derivative plaintiff's demand would have been futile.

His other decisions include Unocal v. Mesa Petroleum, Weinberger v. UOP and Rabkin v. Philip A. Hunt Chemical.

“At a critical time when Delaware law needed to innovate to address the takeover boom of the 1980s, Justice Moore crafted opinions that secured Delaware's role as the forum where all parties knew they would get a fair hearing and a sensible result at the speed demanded by the business world,” the Delaware Judiciary said in a statement. “To this day, his decisions in Unocal v. Mesa Petroleum and Aronson v. Lewis are required reading in any corporate law class in the United States.”

After retiring from the court, Moore took a job as senior managing director of Dresdner Kleinwort Wasserstein, an international investment bank, where he specialized in the areas of mergers and acquisitions and advising special committees of boards of directors. In 1988, Moore started the annual Tulane corporate law conference, which has expanded to include more than 700 participants, including prominent figures from Delaware's bench and bar.

He also taught corporate law and business ethics at Tulane University School of Law, Washington University School of Law and Widener University School of Law.

In 2011, he returned from a second retirement to expand Gibbons' practice in Wilmington, where he worked with his son-in-law, Christopher Viceconte, director of the Wilmington office's commercial and corporate litigation practice.

Arthur L. Dent, a partner with Potter Anderson & Corroon, said Moore was already seen as a corporate law giant by the time he clerked for the judge in the summer of 1985. Dent described Moore as “principled and demanding” boss, who stressed the importance of honesty and integrity.

“People who came to work with him really adored him,” Dent said. “I was a little bit awed [by him], but we hit it off and became lifelong friends. In many ways, I considered him family.”

“It's a huge loss for the legal community and the community at large,” he said.

Viceconte met Moore in 2004, after he started dating Moore's daughter Marianne. Viceconte said Moore was a generous mentor, who shaped his life both personally and professionally.

“My relationship from Day 1 was Drew,” he said. “He was just a great friend—extremely fun to be around, never said no to anything and loved his family.”