University of Hawaii law professor Jon Van Dyke was a leading authority on Native Hawaiian, U.S. constitutional, environmental and international issues.

But the dozens of colleagues, students and other admirers who gathered at Van Dyke’s classroom Wednesday commemorated the man who made a lasting impression on them personally.

Van Dyke, 68, died Tuesday night unexpectedly in his sleep in Melbourne, Australia. He had been expected to deliver the keynote speech at a conference on ocean-related law.

Conference organizers realized something was wrong when he didn’t show up to deliver the address, said Avi Soifer, dean of the UH William S. Richardson School of Law.

"He has greatly influenced the development of law not only in the state of Hawaii, but internationally," said Hawaii Supreme Court Justice Sabrina McKenna, a former student and later fellow professor at Richardson. McKenna was among those attending a memorial at Van Dyke’s constitutional law classroom.

As important as his worldwide influence was on legal issues, "he was someone who taught us to think critically, to be open-minded and respectful of different points of view," she said. "He taught all of us about professionalism, and treating people with respect, and the importance of standing up for the underdog and the cause of justice."

That theme was echoed by generations of students at the law school where Van Dyke had taught since 1976.

Maile Osika, a third-year law student, had been a researcher for Van Dyke since she began law school; Van Dyke was a hero to her from before that, she said.

Osika said her mentor genuinely valued a person’s opinion regardless of position or standing, she said.

"He never took a student’s work for granted and he really cared about your ideas," Osika said. "He would never make you feel like he already had an opinion on something, or that you couldn’t change your mind. It always felt like whatever he said was going to be taken into consideration."

Melissa Pavlicek, a 1996 graduate who started out as a lawyer and later began a government relations company, said: "He made me feel like I could use my lawyering skills to help have an effect at the state Capitol on public policy and that you really had to do that to make the world a better place."

Soifer described Van Dyke as a low-key but brilliant professor, researcher and educator who excelled in a multiple areas of law, including Native Hawaiian rights, human rights, constitutional law and international law related to islands and the sea.

UH land use law professor David Callies, a colleague for 35 years, said Van Dyke’s work was seminal in a number of areas but perhaps no more so locally than in the area of Native Hawaiian rights.

"Native Hawaiian interests and rights would not be where they are today without Jon Van Dyke and (his wife) Sherry Broder," Callies said. "They often worked as a team. Jon provided the academic heft."

Despite being a strong civil rights advocate, Van Dyke also was instrumental in city ordinances governing signage and T-shirt sales. Civic responsibility was as important to Van Dyke as civil rights, Callies said.

Internationally, Van Dyke helped political victims of the Ferdinand Marcos regime and was instrumental in the development of international law, particularly related to the oceans, Callies said.

UH water rights professor Williamson Chang said Van Dyke’s zeal for helping Native Hawaiians and other small water users in their fight against powerful sugar interests nearly cost him his tenure.

"The big companies stepped into the university process and asked that his tenure application be delayed," Chang said.

U.S. Sen. Daniel Akaka said in a statement that Van Dyke inspired both his students and the community. "Because of Jon’s work, the principle of protecting our cultural and historic resources has been preserved, and the tradition of sharing the resources of our beautiful beaches and other natural resources with all continues to be honored."

As a young law professor, Van Dyke was deeply involved in the 1978 state Constitutional Convention, a pivotal point in modern Hawaii politics. The convention led to the establishment of the Office of Hawaiian Affairs to try to provide redress to the Hawaiian people.

"Jon was very instrumental in helping the various Hawaiian groups that were active at the time," said former Gov. John Waihee, a convention delegate.

Gov. Neil Abercrombie also recalled Van Dyke’s work in the establishment of OHA.

"Jon was an invaluable resource," Abercrombie said in a statement. "His intellect brimmed over with energy and brilliance. He was a patient, calming influence in every instance of tension and conflict."

Van Dyke was one of the longest-serving members of the faculty. He previously taught at Hastings College of the Law, University of California, San Francisco, and at the Catholic University Law School, Washington, D.C.

Van Dyke was the author of six books, including "Who Owns the Crown Lands of Hawai‘i?" in 2008, "Jury Selection Procedures: Our Uncertain Commitment to Representative Panels" in 1977, and "North Vietnam’s Strategy for Survival" in 1972. He was also editor of five additional volumes related to issues surrounding law of the sea.

He served as the UH law school’s associate dean from 1980 to 1982. He was also director of the Spark M. Matsu­naga Institute for Peace from 1988 to 1990, and was an adjunct research associate or fellow at the East-West Center from 1979 to 1991 and from 2000 to 2011, according to his biography.

Van Dyke was the recipient of a University of Hawaii presidential citation for excellence in teaching in 1987, and was selected outstanding professor at the law school on four occasions.

He graduated from Harvard Law School in 1967.

He is survived by his wife, attorney Sherry Broder. They have two sons, Jesse Broder Van Dyke, a spokesman for Akaka, and Eric; and daughter Michelle.