In 2000, Buckel was the lead lawyer for the estate of Brandon Teena, a transgender man who was raped and murdered in Nebraska, when Teena's family recovered damages against negligent law enforcement officers. Buckel stated, "It's a very important case, not only within Nebraska but nationally." The story inspired the 1999 biographical film Boys Don't Cry.
Fox News called Buckel "a pioneering lawyer for gay and transgender rights." In a statement to the Huffington Post, Camilla Taylor, senior staff attorney for Lambda Legal, stated, "His thoughtful and engaging advocacy broke through many stubborn misconceptions and showed it was possible and necessary for our movement to speak up for bullied, ostracized LGBT young people." Susan Sommer, a former attorney for Lambda Legal, called Buckel "one of the architects of the freedom to marry and marriage equality movement."
At the time of his death, Buckel was senior organics recovery coordinator with the NYC Compost Project. He previously was a volunteer coordinator of Added Value Red Hook Community Farm, where he practiced composting. He was nominated for a Solid Waste Association of North America Unsung Hero Award for his work in composting and for the environment.
Buckel wrote Guidelines for Urban Community Composting, a guide for composting in urban areas.
Buckel and his husband, Terry Kaelber, were raising a daughter, Hannah Broholm-Vail. They co-parented Hannah with Rona Vail and Cindy Broholm.
On April 14, 2018, Buckel's body was found by a passerby in Brooklyn's Prospect Park. It appeared that he had burned himself to death. Next to the body was a note in a manila envelope marked "To the police". The text of the note, which also was emailed to The New York Times, stated: "Most humans on the planet now breathe air made unhealthy by fossil fuels, and many die early deaths as a result—my early death by fossil fuel reflects what we are doing to ourselves."
Buckel had left his identification on a lanyard nearby and stapled his business card to the letter to aid in identification, in which he wrote to the police, "I apologize to you for the mess." A folding shopping cart with an empty plastic bag of the type used to haul soil in it was nearby; as the earth around Buckel was burned in a nearly perfect circle, The New York Times speculates that he had made a ring of soil to prevent the fire from spreading.
Logue, P. M.; Buckel, D. S. (1996). "Fighting Anti-Gay Abuse in Schools: The Opening Appellate Brief of Plaintiff Jamie Nabozny in Nabozny v. Podlesny". Michigan Journal of Gender & Law. 4: 425.
Buckel, David S. (26 July 2016). "Legal Perspective on Ensuring a Safe and Nondiscriminatory School Environment for Lesbian, Gay, Bisexual, and Transgendered Students". Education and Urban Society. 32 (3): 390–398. doi:10.1177/0013124500323007.
Buckel, D. S. (2005). "Same-Sex Couples: Defining Marriage in the Twenty-First Century: Government Affixes a Label of Inferiority on Same-Sex Couples When It Imposes Civil Unions & Denies Access to Marriage". Stanford Law & Policy Review. Stanford Law School. 16: 73.