Edward de Grazia, a First Amendment lawyer who won landmark obscenity cases in which he defended such literary works as Henry Miller’s “Tropic of Cancer” and William Burroughs’s “Naked Lunch,” died April 11 at the Potomac Valley Nursing & Wellness Center in Rockville. He was 86.

He had Alzheimer’s disease, his son David de Grazia said.

Mr. de Grazia, who practiced law and taught at several Washington law schools, was one of the country’s foremost advocates of the First Amendment, championing the causes of writers, publishers, filmmakers and others who challenged legal and moral conventions.

He did his most notable work in the 1960s, when he defended the controversial comedian Lenny Bruce and won major legal victories that permitted the distribution of “Tropic of Cancer,” “Naked Lunch” and the Swedish film “I Am Curious (Yellow).” Mr. de Grazia was also a playwright and the author of a comprehensive history of literary censorship, “Girls Lean Back Everywhere: The Law of Obscenity and the Assault on Genius” (1992).

He was, in the words of a onetime colleague, legal scholar Monroe Price, “the exemplar of a public interest scholar-lawyer: not only a teacher, but one who fought in the courts for principles in which he believed.”

Edward de Grazia successfully argued that several literary works, including William Burroughs’s ‘Naked Lunch’ and Henry Miller’s ‘Tropic of Cancer,’ as well as the film ’I Am Curious (Yellow),’ had artistic merit and should not be banned as obscene by the courts. (Cardozo School of Law)

Mr. de Grazia began working on censorship cases in the early 1950s, soon after he began his career in the Washington office of Kirkland, Green, Martin and Ellis. In 1955, he defended a bookseller who was seeking to import a copy of the play “Lysistrata,” written more than 2,000 years earlier by Aristophanes, one of the classic playwrights of ancient Greece.

The U.S. Postal Service seized an illustrated copy of the play, deeming it obscene. Mr. de Grazia ultimately won an injunction against the Postal Service.

In the early 1960s, he began to handle cases for Barney Rosset, whose Grove Press published books by Miller and Burroughs and other writers who dealt with overtly sexual matters. Miller’s “Tropic of Cancer,” an autobiographical novel about a struggling writer in Paris, had been banned in many states for being lewd.

Mr. de Grazia structured his argument around a 1957 U.S. Supreme Court decision, Roth v. United States, in which Justice William J. Brennan Jr. wrote that material could be banned if it was “utterly without redeeming social importance” or appealed primarily “to the prurient interest.”

By demonstrating that “prurient interest” did not negate “social importance,” Mr. de Grazia won a 5-4 Supreme Court decision in 1964, overturning a lower-court ruling that outlawed the sale of “Tropic of Cancer.”

Mr. de Grazia returned to the literary battlefield in 1965 with a new tactic to defend Burroughs’s “Naked Lunch,” a 1959 novel about the reflections of a heroin addict. After the book had been banned in Boston, Mr. de Grazia called on writers Norman Mailer and Allen Ginsberg to judge its merits.

The writers’ courtroom testimony — often eloquent and sometimes baffling — tied the prosecution in knots of bewilderment, as it became apparent that “Naked Lunch” contained artistic and political themes that went far beyond its occasional depictions of sexual acts.

The ban on the book was tossed out by a Massachusetts court, and “Naked Lunch” is now hailed as a masterpiece of the Beat Generation.

One writer who did not testify on behalf of “Naked Lunch” was its author.

“De Grazia considered bringing Burroughs himself as a witness,” William Thomas Lawlor noted in the book “Beat Culture,” “but decided to drop that idea when [he] recalled the fact that Burroughs had shot and killed his wife in Mexico.”

Edward Richard de Grazia was born Feb. 5, 1927, in Chicago. His father was a bandleader, and Mr. de Grazia played the clarinet in his youth.

He served in the Army in Europe and graduated in 1948 from the University of Chicago, where he also received a law degree in 1951.

After practicing law in Washington, he worked for UNESCO in Paris from 1956 to 1959, then spent two years in New York before returning to Washington in 1961. He taught occasionally at Georgetown, Catholic, American and Howard universities.

In 1967, after Mailer was arrested in an antiwar protest in Washington, Mr. de Grazia helped get him and other demonstrators released from jail. Mailer wrote about the incident in Harper’s magazine and his book “Armies of the Night.”

In one of his last major cases, Mr. de Grazia won an appeals court ruling in 1969 that allowed theaters to show the film “I Am Curious (Yellow).”

Mr. de Grazia was a founding faculty member of the Cardozo School of Law at Yeshiva University in New York in 1976. He retired in 2006.

His marriages to Ellen O’Connor, Elisabeth Goode and Lora Price ended in divorce.

A son from his first marriage, Augustus de Grazia, died in 2011.

Survivors include four children from his first marriage, Belinda Holtzclaw of Houston, Christophe de Grazia and Elizabeth Blumenfeld, both of Washington, and David de Grazia of Silver Spring; a brother; and three grandchildren.

Mr. de Grazia wrote about a dozen plays, some of which were performed in New York and at Arena Stage in Washington, and a textbook on obscenity law.

His 1992 book, “Girls Lean Back Everywhere,” was considered an authoritative study of artistic censorship, touching on works by James Joyce, Theodore Dreiser, Vladimir Nabokov, D.H. Lawrence, artist Robert Mapplethorpe and even the rap group 2 Live Crew.

In short, Mr. de Grazia believed the government had no right to control the content of printed and visual works and that laws against obscenity were, on their face, an affront to liberty.

He was, as he sometimes described himself, a “defender of dangerous books and films.”