Flanders began his legal career in New York as associate with the firm of Paul, Weiss, Rifkin, Wharton & Garrison in litigation law. He returned to Rhode Island in 1975, and the firm of Edwards & Angell, where he became a partner and Chairman of the firm's Litigation Department. He also served as assistant executive counsel to the Governor of Rhode Island. He elected to the Town Council of Barrington, where he served for two terms. He later became the town solicitor for Glocester, Rhode Island and general counsel to the Rhode Island Solid Waste Management Corporation. In 1987, he founded his own business and government litigation firm, Flanders and Medeiros. In 1996, after serving as special prosecutor for the Judicial Tenure and Discipline Commission and being chosen as one of five finalists by a judicial merit-selection commission, Governor Lincoln Almond named Flanders to a vacant seat on the five member Rhode Island Supreme Court. On March 29, 1996, Flanders was sworn in as one of the five Justices of the Rhode Island Supreme Court. In 2004, after eight years of service on the Supreme Court, Justice Flanders resigned to return to private law practice as a partner in the law firm of Hinckley, Allen & Snyder. He has also served as a Distinguished Visiting Professor of Law at the Roger Williams University Law School, where he has taught constitutional law and judicial process courses, and as an Adjunct Assistant Professor of Law and Public Policy at Brown University, where he taught courses on constitutional theory and the judicial process. Flanders serves as a member of various boards of directors and commissions, including the CARE New England Hospital system, Women & Infants Hospital, the Providence Performing Arts Center, the Veterans Memorial Auditorium, the Rhode Island Historical Society, Common Cause of Rhode Island, the Brown University Leadership Advisory Council, and the Greater Providence YMCA, where he served as Chairman of the Board for a three-year term that ended on May 29, 2003.
2018 Senate campaign
Flanders won the Republican party nomination, defeating the only other candidate on the ballot, Rocky De La Fuente, a businessman who was seeking to get on the Senate ballot in several states in 2018. In the general election of November 6, 2018, he lost to incumbent Sheldon Whitehouse, receiving 38% of the vote to Whitehouse's 61%.
