The son of a physician, Kunstler was born in New York City and attended DeWitt Clinton High School. He was educated at Yale College, graduating Phi Beta Kappa in 1941, and Columbia University Law School from which he graduated in 1948. While in school, Kunstler was an avid poet and represented Yale in the Glascock Prize competition at Mount Holyoke College. Kunstler served in the U.S. Army during World War II in the Pacific theater, attaining the rank of Major, and received the Bronze Star.

In 1974-1975, Kunstler defended a prisoner charged with killing a guard during the Attica Prison riot. Under cross-examination, Kunstler forced Correction Officer Donald Melven to retract his sworn identification of John Hill, Kunstler's client, and Charles Pernasilice (defended by Richard Miller), admitting he still retained "slight" doubts that he confessed to investigators at the time of the incident. Kunstler focused on pointing out that all the other prosecution witnesses were testifying under reduced-sentencing agreements and called five prison inmates as defense witnesses (Miller called none), who testified that other prisoners hit the guard.  Despite Justice King's repeated warnings to Kunstler to "be careful, sir", Kunstler quickly became "the star of the trial, the man the jurors watch most attentively, and the lawyer whose voice carries most forcefully". Although the prosecution was careful to avoid personal confrontation with Kunstler, who frequently charmed the jury with jokes, on one occasion Kunstler provoked a shouting match with the lead prosecutor, allegedly to wake up a sleeping jury member. The jury convicted Hill of murder and Pernasilice of attempted assault. When Kunstler protested that the defendants would risk being murdered due to the judges remanding them, King threatened to send Kunstler with them. New York Governor Hugh Carey granted executive clemency to Hill and the other inmates in 1976, even though Hill's name was not on the recommended list of pardons delivered to the governor and his appeals were still pending.  In June, Kunstler and Barbara Handshu, representing another inmate at Attica, Mariano Gonzales, asked for a new hearing on the role of FBI informant Mary Jo Cook. Answer this question using a quote from the following article:

How did the jury react to Kunstler in the John Hill case?
Kunstler, who frequently charmed the jury with jokes,