Dershowitz has been noted as a criminal appellate lawyer, most notably in getting a conviction overturned for Claus von Bülow, who had been accused of trying to murder his wife. The publicity surrounding this New York society scandal fueled enough interest that Dershowitz's book on the case, Reversal of Fortune, was turned into a major film starring Jeremy Irons and Glenn Close. In addition, Dershowitz has often commented on Judaism, Israel, civil rights and liberties, and the First Amendment.

Early life, education, and family
Dershowitz was born in the Williamsburg neighborhood in the New York City borough of Brooklyn and grew up in Borough Park.

His parents, Harry and Claire, were both devout Orthodox Jews. Harry Dershowitz (May 8, 1909–April 26, 1984) was a founder and president of the Young Israel Synagogue in the 1960s, served on the board of directors of the Etz Chaim School in Borough Park, and in retirement was co-owner of the Manhattan-based Merit Sales Company. Dershowitz's brother Nathan is counsel for the American Jewish Congress.

Dershowitz attended Yeshiva University High School, where he played on the basketball team. He was a rebellious student, often criticized by his teachers. The school's career placement center, however, told him that he had talent and was capable of becoming an advertising executive, funeral director, or salesman. He decided, he said, to do something that "requires a big mouth and no brain...so I became a lawyer."

Upon graduating, he attended Brooklyn College and received a Bachelor of Arts degree in 1959. He later attended Yale Law School, where he was editor-in-chief of the Yale Law Journal. He graduated first in his class with a Bachelor of Laws (LL.B.) in 1962.

Career
After being admitted to the bar, Dershowitz served as a law clerk for David L. Bazelon, Chief Judge of the U.S. Circuit Court of Appeals for the District of Columbia, and Arthur Goldberg, Associate Justice of the U.S. Supreme Court.

He joined the faculty of Harvard Law School as an assistant professor of law in 1964. He was made a full professor of law in 1967 at the age of 28, becoming Harvard's youngest full law professor in the law school's history. He was appointed the Felix Frankfurter Professor of Law in 1993, succeeding Abram Chayes.

Much of Dershowitz's legal career has focused on criminal law, and his clients have included high-profile figures such as Patricia Hearst, Leona Helmsley, Jim Bakker, Mike Tyson, O.J. Simpson, and Harry Reems.

Dershowitz also played a leading role in the prosecution of John Demjanjuk, who in 1988 was convicted in Israel for crimes committed by "Ivan the Terrible of Treblinka"; the decision was overturned by the Israeli Supreme Court in 1993.

While representing Claus von Bülow he had the case overturned on appeal; in a retrial, von Bülow was acquitted. Afterwards, Dershowitz told the story of the case in his book, Reversal of Fortune. In the movie version, Dershowitz was played by Ron Silver and also himself had a cameo as a judge.

For several years, Dershowitz has written the monthly column "Justice" in the pages of Penthouse (magazine).

Recognition
Dershowitz was named a Guggenheim Fellow in 1979, and was in 1983 a recipient of the William O. Douglas First Amendment Award from the Anti-Defamation League of the B'nai Brith for his work in civil rights. He has been awarded honorary doctorates in law from Yeshiva University, the Hebrew Union College, Monmouth College,Haifa University and Bar-Ilan University.

He has been described by Newsweek as America's "most peripatetic civil liberties lawyer and one of its most distinguished defenders of individual rights", and by Corriere della Sera as "America's most famous progressive lawyer".

He has been referenced on several occasions in popular entertainment, especially during the O.J. Simpson trial. On television, he has been parodied on Saturday Night Live and mentioned in the episode "Homer Bad Man" of The Simpsons.

Views and positions
Dershowitz has taken public stances on a number of controversial contemporary issues. Because of his fame, his positions have often been covered by major media sources and have been the subject of attention from both scholarly and political points of view.

Torture warrants
Following the September 11, 2001 attacks, Dershowitz advocated the issuance of warrants allowing terrorism suspects to be tortured if there is an "absolute need to obtain immediate information in order to save lives coupled with probable cause that the suspect had such information and is unwilling to reveal it".

Although he claims to be personally against the use of torture, he believes that authorities should be permitted to use non-lethal torture in a "ticking bomb" scenario, regardless of whether international law permits it, and that it would be less destructive to the rule of law to regulate the process than to leave it up to the discretion of individual law-enforcement agents. Under his proposal, the government would not be allowed to prosecute the torture subject based upon information revealed under that interrogation method. "If torture is going to be administered as a last resort in the ticking-bomb case, to save enormous numbers of lives, it ought to be done openly, with accountability, with approval by the president of the United States or by a Supreme Court justice".

Some civil libertarians have criticized Dershowitz's solution to the problem presented by uncooperative captured terrorists. Harvey Silverglate states that jury nullification and executive clemency could protect law enforcement in the hypothetical ticking-bomb case, thus "our legal system is perfectly capable of dealing with the exceptional hard case without enshrining the notion that it is okay to torture a fellow human being".

William F. Schulz, the executive director of the U.S. section of Amnesty International, states that Dershowitz's hypothetical ticking-bomb scenario is unrealistic, because it would require that "the authorities know that a bomb has been planted somewhere; know it is about to go off; know that the suspect in their custody has the information they need to stop it; know that the suspect will yield that information accurately in a matter of minutes if subjected to torture; and know that there is no other way to obtain it." He also states that employing authorized torture would lower the country's ability to stand up for human rights abroad.

Bill Goodman of the Center for Constitutional Rights, debating with Dershowitz on CNN, stated that Dershowitz's proposal would create a "very slippery slope," and that torture would "happen under more than those exceptional circumstances. It's going to start becoming the regular, rather than the unusual".

The debate with Finkelstein
Shortly after the publication of Dershowitz's book The Case for Israel, Norman Finkelstein accused Dershowitz, of "fraud, falsification, plagiarism and nonsense." Dershowitz and Finkelstein argued the question on an episode of Democracy Now!; Finkelstein later expanded the charges into a book, Beyond Chutzpah. After repeated attempts to block the book's publication, Alan Dershowitz wrote in Front Page Magazine that Finkelstein suspected his own mother (a Holocaust survivor) of being a Nazi Kapo. Finkelstein responded by indicating that he had never made such a comment and urged his readers to mail Harvard University to fire Dershowitz. This correspondence can be found on Finkelstein's website, along with the article from his memoir, which instigated Dershowitz's writing on this matter.

Mearsheimer and Walt Paper
Fellow Harvard professor John Mearsheimer and Stephen Walt of Chicago University, both political scientists published in March 2006 a paper which criticizes what they describe as the "Israel Lobby" for influencing U.S. foreign policy in the Middle East away from U.S. interests and towards Israel's interests. They denote Alan Dershowitz in the paper as playing the role of an "apologist" for the Israeli lobby. In response, Dershowitz wrote an extensive report that challenged both the factual basis of the report, the motivations of the authors and their scholarship. Dershowitz claimed that the "paper contains three types of major errors: quotations are wrenched out of context, important facts are misstated or omitted, and embarrasingly weak logic is employed."