The Anti-Defamation League announced last week that Needham resident Robert O. Trestan has been appointed director of the national organization’s New England office, based in Boston. Trestan has been with the organization since 2005, providing legal guidance to its six regional offices in the Northeast. The Anti-Defamation League responds to hate crimes, extremist activities, legislation, discrimination complaints, and church-state issues. Trestan was the leader of a broad coalition that won passage of antibullying legislation in Massachusetts in 2010, organization officials said. He served for more than a decade as director of civil rights at the Boston Housing Authority, and worked for four years as an assistant public defender in Naples, Fla.