Carter was eventually released from detention and began serving in the armed forces. He learned to box. After returning to New Jersey, Carter was again arrested by authorities who maintained that he had not fulfilled his entire sentence. He was returned unceremoniously to prison to serve the remaining 10 months of his term.

Upon his release, Carter began boxing professionally. He amassed a solid record, including a series of knockouts brought on by his furious punching style. A sportswriter gave him the nickname "Hurricane", and it stuck. Carter continued to rise through the middleweight ranks, at one point knocking out the legendary Emile Griffith. He was ready for a shot at the title.

Unfortunately, fate would intervene. On June 17, 1966, three white patrons were gunned down at the Lafayette Bar and Grill in Paterson. Carter and an acquaintence named John Artis were arrested and eventually tried for the killings. Though the state's evidence depended largely on the shaky testimony of two former convicts, Carter and Artis were convicted by an all-white jury of the murders. They were sentenced in 1967 to life behind bars.

Carter refused to behave like other prisoners. This stemed from his belief that he was not a criminal; therefore, he should not be treated like one. He did not eat the prison's food and wear prison garb. He rarely left his cell and concentrated mostly on reading books and writing.

In 1974, he published "The Sixteenth Round", his version of the events that led to his incarceration, as well as portrait of his life in prison. He gained celebrity from it, and Bob Dylan wrote a song entitled "Hurricane" that chronicled Carter's case and his suffering.

In 1976, Carter was retried after a brief period of being on parole. Both of the earlier key witnesses had changed their stories. Nevertheless, the result was the same. Carter and Artis were returned to prison after a second conviction.

Help would come for Carter from one of the unlikliest of sources. In addition to his attorneys, by the early 1980s he had the help of several young Canadians. The group had been raising a young black kid named Lesra Martin. Martin, learning to read as a teenager, purchased a used copy of Carter's book and read it. He began a correspondence with Carter, enlisting the help of the Canadians to help Carter prove his innocence.

Over several years, the group and Carter's lawyers fought for hearings to show that Carter had been denied a right to a fair trial. Finally, on November 7, 1985, Federal District Judge H. Lee Sarokin freed Carter after Sarokin wrote that the convictions were based on racial prejudices and not facts. Artis had been released on parole 4 years earlier.