He began his career as a prison guard or assistant warden at the state prison in Wethersfield, Connecticut in 1848. Brockway became a clerk at the Wethersfield prison by 23 years old. Later he worked as assistant superintendent of the Municipal Alms House in Albany, New York for four years. He was made the Monroe County, New York Penitentiary superintendent in 1854. There, he focused upon rehabilitation of the prisoners. In 1861, Brockway became the superintendent of the prison in Detroit, where he attempted to introduce work and release supervision programs and "indeterminate sentences". Brockway's chief innovation, though, was his attempt to establish the country's first indeterminate sentencing system. In 1869, Brockway drafted a law, passed by the Michigan legislature but overturned by the state Supreme Court, that would allow for the conditional and discretionary release of “common prostitutes.”
When he was in Detroit, he got the inspiration for his prison reforms from Moses and Amos Pilsbury, who also brought about prison reforms. He began his reforms in Detroit however, resigned in 1872 when his ideas were no longer accepted.
Before the Elmira Reformatory was built, Brockway was already made the superintendent in 1876. While warden at the Elmira Reformatory in Upstate New York from 1876 to 1900, Brockway introduced a program of education, training in useful trades, physical activity, indeterminate sentences, inmate classification, and an incentive program. Brockway believed that the primary reason to have a prisoner in custody was to rehabilitate and not simply just to punish. By giving them the moral and spiritual guidance that they needed, Brockway believed that this was the key to helping them become better and useful citizens. He also used the idea of indeterminate sentence which would allow a prisoner to get parole sooner than he expected, because Brockway did not believe in fixed sentences either. His rules had two sides. One side was if a prisoner was well behaved and abided by the rules, then he would be rewarded. If a prisoner did not abide by the rules then he would be punished. These sets of rules came under scrutiny.
In 1893, his administration endured investigation into accusations of brutality at Elmira, but he retired at the age of 72 in 1900 after further criticism. Brockway was such a popular man in Elmira that he was elected mayor five years later at 77.
In 1912, he wrote Fifty Years of Prison Service: An Autobiography (1912).
Zebulon Brockway died in 1920 at the age of 92.
- James J. Beha, Redemption to Reform: The Intellectual Origins of the Prison Reform Movement, New York University Annual Survey of American Law, vol. 3, 773, 2007–2008.
- Todd R. Clear, George F. Cole, Michael D. Reisig (2006). American Corrections. Cengage Learning. pp. 50–51. ISBN 978-0-534-64652-3. Retrieved August 20, 2010. "Brockway even weathered an 1893 state investigation into charges of brutality at Elmira, which revealed that the whip and solitary confinement were used there regularly. However, in 1900 he was forced to resign in the face of mounting criticism of his administration."
- "Fifty Years of Prison Service: An Autobiography : Zebulon Reed Brockway : Free Download & Streaming : Internet Archive". Archive.org. 2001-03-10. Retrieved 2013-06-13.