James R. Milkey was born in Hartford, Connecticut, on December 17, 1956. He earned a B.A., magna cum laude, from Harvard College in 1978 and a J.D., magna cum laude, from Harvard Law School in 1983. He also received a master's degree in city planning from MIT that year. Justice Milkey began his legal career serving as a law clerk to Justice Benjamin Kaplan of the Appeals Court during the 1983-1984 term. He then joined the environmental protection division of the Massachusetts Attorney General's office. He became chief of the division in 1996. He served as counsel of record in Massachusetts v. EPA, which addressed the Environmental Protection Agency's responsibility to regulate greenhouse gas emissions under the Federal Clean Air Act, and successfully argued that case before the United States Supreme Court. Justice Milkey has lectured frequently on climate change, enforcement, brownfields, and regulatory takings issues. From 2003 to 2005, he was co-chair of the environmental law section of the Boston Bar Association. He was a visiting associate professor at Pace Law School in New York and co-taught a course at Harvard Law School.
Justice Milkey has received numerous awards, including being named Public Servant of the Year by the Environmental League of Massachusetts in 2006. In 2007 he was named one of ten "Lawyers of the Year" by Lawyers USA, and the American Bar Association honored him with its annual Award for Distinguished Achievement in Environmental Law and Policy. The following year, the Massachusetts Association of Conservation Commissions recognized Justice Milkey with an award for outstanding public service, and in 2009 he received a lifetime achievement award from the Environmental Protection Agency-New England. Appointed to the Appeals Court by Governor Deval Patrick, Justice Milkey joined the court on April 8, 2009. He and his wife have two sons.