Buckel was marriage project director for Lambda Legal, and in that position he persuaded the organization to file a suit for marriage rights in Iowa in 2005, "at a time when only MA permitted same-sex couples to marry", noted a statement released by Camilla Taylor, the group's director of constitutional litigation and acting legal director.
"Honourable goal in life invites honourable objective in death".
Buckel left a note nearby where his body was found.
He headed up Lambda Legal's defense team that secured justice from the state of Nebraska for the rape and murder of transgender man Brandon Teena in 1993.
The remains of David Buckel, 60, were found by civilians passing through the NY park, and police say he was pronounced dead at around 6:30 a.m EST. The case inspired the Oscar-winning 1999 movie "Boys Don't Cry", directed by Kimberly Pierce and featuring Hilary Swank as Teena. Image credit: Getty " Many who drive their own lives to help others often realize that they do not change what causes the need for their help", expressed Mr. Buckel on his note, adding that donating to organizations was not enough.
"A lifetime of service may best be preserved by giving a life..."
Buckel set himself on fire with fossil fuels.
Buckel was found when firefighters responded to reports of a fire in Prospect Park, the police spokesperson said.
He argued against the Boy Scout ban on gay, fought for the right of gay high school students in Salt Lake City to organize a club and helped a Pennsylvania woman win a lawsuit allowing her to put "beloved life partner" on the headstone of her partner.
'Amadeus' director Milos Forman dies at 86
In this file photo taken on October 09, 2009 Czech-born United States film director Milos Forman poses in Paris. Starring Jack Nicholson , the film was an adaptation of Ken Kesey's 1962 novel of the same name.
'The thoroughness, the detail and the careful reasoning in the opinion means that other courts around the nation will be paying attention, ' he said.
The organisation said he had won several key court victories including in the Lewis v Harris case, in which the New Jersey Supreme Court recognised the harm done to same-sex couples and their children from being excluded from the rights and responsibilities of marriage.
He was also a nationally renown pioneer in #CommunityComposting and one of my mentors.
Buckel ran the NYC Composting Project out of Red Hook Community Farm.
Tributes have begun to pour in for Buckel, with Lambda Legal calling his death a loss for the "entire movement for social justice".
Sommer added, "He was a very smart and methodical lawyer".
"Our thoughts and condolences go out to all those who loved David", Taylor concluded".
After leaving Lambda Legal, Buckel focused his career on fighting for environmental causes, The New York Times said.