Judge Riley graduated from Villanova University in 1964 and from its law school in 1967. He then served in the United States Army for two years, including a tour in the Republic of South Vietnam. Upon completion of his military service, he entered the practice of law in 1969 in Philadelphia. In 1971 he opened his office in Chester County. In 1972, he co-founded the firm of Malcolm & Riley, P.C. where the focus of his practice was civil litigation. He was involved in a leadership capacity in numerous professional organizations. In November of 1992 he was appointed Judge of the Court of Common Pleas of Chester County by Governor Robert P. Casey, taking office in December 1992. The following year he was elected to a ten year term on the Court of Common Pleas. He was elected President Judge of the court and served in that capacity from January 2000 to January 2005. In 2003, Judge Riley was retained by the voters of Chester County for a second ten year term.

Judge Riley is a life member and former director and president of the Goshen Fire Company, a charter member of the Westtown-Goshen Rotary Club and has been involved in numerous community organizations and activities.