John M. Greaney was born on April 8, 1939, in Westfield. He received his B.A., with honors, from the College of the Holy Cross in 1960 and his J.D. from New York University School of Law in 1963, where he was a Root-Tilden scholar and chairperson of the Annual Survey of American Law. After briefly serving in the military, Chief Justice Greaney joined the Springfield law firm of Ely and King until his appointment to the Hampden County Housing Court in 1974.
Chief Justice Greaney served as presiding judge in the Housing Court until Governor Michael Dukakis appointed him to the Superior Court in 1975, then to the Appeals Court in 1978. He served as an associate justice until 1984, when he became the Court's chief justice. In 1989 Chief Justice Greaney was appointed to the Supreme Judicial Court, where he served until his retirement in 2008. During his tenure on the Supreme Judicial Court, Chief Justice Greaney participated in several landmark cases. He wrote the concurrence in Goodridge v. Department of Public Health, making Massachusetts the first State to legalize same-sex marriage.
Currently, Chief Justice Greaney is director of the Macaronis Institute for Trial and Appellate Advocacy at Suffolk University School of Law. Justice Greaney has taught law and lectured extensively, edited several books on the law of deceptive and unfair practices and appellate practice and procedure, and co-authored books on civil jury instructions and summary judgment.