Bill Babbitt is an activist in the abolition movement. He regularly speaks out against the capital punishment system after promising his younger brother Manny he would campaign to end the death penalty. On May 4, 1999 Bill Babbitt witnessed fifty-year-old Manny Babbitt's execution by the State of California at San Quentin prison.

The sons of an émigré from the Cape Verde Islands off the coast of western Africa, Manny and Bill Babbitt grew up in a family of eight children in Wareham, Massachusetts. Enlisting in the Marines as a teenager, Manny Babbitt served two tours of duty in Vietnam, including fighting at the siege at Khe Sanh in 1968. He later received a Purple Heart for wounds sustained during his military service in 1998, while a prisoner on Death Row.

In the years following his discharge Manny Babbitt lived in Massachusetts and Rhode Island where he suffered from schizophrenia and post-traumatic stress disorder. According to Carbone, he spent time in psychiatric institutions, failed at relationships, lived periodically on the streets, drank and engaged in drug use, and went to prison for committing increasingly violent crimes. He moved in September 1980 to Sacramento, California to be with his brother Bill and sister-in-law Linda. There Manny Babbitt was ultimately tried and convicted of the murder of an elderly woman, Leah Schendel, who died of cardiac arrest after being severely beaten during a robbery in her home in December 1980.

After discovering his brother might be involved in this crime, Bill Babbitt approached the police and assisted them with the arrest of Manny Babbitt. Bill Babbitt states the authorities promised his brother would receive psychological help and placement in a mental health facility rather than on Death Row. In 1982, however, after being found sane and guilty of murder, Manny Babbitt was sentenced to death. According to Doyle, his family strongly believes that his initial lawyers were not competent nor did they offer post-traumatic stress disorder as part of the defense. While Manny Babbitt never denied committing the crime, he stated he could not remember anything about that night.

During the 1990s Manny Babbitt had a new legal defense team dedicated to trying to appeal his conviction, secure a new trial, and spare his life through legal channels. It was led by public defender and lead counsel Jessica McGuire and a fellow Vietnam veteran and trial attorney Chuck Patterson. In addition to Manny and Bill Babbitt's family and supporters, other Vietnam veterans also petitioned California Governor Gray Davis for clemency in this case. Both legal activity and media coverage of the case intensified in the early months of 1999, leading up to Governor Davis denying clemency, several high courts rejecting last minute appeals and intervention, and Manny Babbitt's subsequent execution.

Bill Babbitt continues to campaign against the death penalty and is frequently interviewed on network television news programs, radio stations, major daily newspapers, and magazines. He attends anti-death penalty rallies, testifies before state legislative committees, and often speaks alongside David Kaczynski, the executive director of New Yorkers Against the Death Penalty, before student and legal groups. David Kaczynski assisted federal authorities with the apprehension of his brother Ted Kaczynski, known as the "Unabomber." The documentaries And Then One Night: The Making of Dead Man Walking with Sister Helen Prejean and Mike Farrell and A Question of Justice, also with David Kaczynski, share the story of Bill and Manny Babbitt.

Bill Babbitt is active in several national organizations that oppose capital punishment. He was a board member of Murder Victims' Families for Reconciliation from 2000-2004 and is a founding board member of Murder Victims' Families for Human Rights, where he still serves today.