At 24, he was elected to Stormont as a Nationalist member for East Tyrone. In June 1968, he occupied a house in Caledon, Tyrone in protest over allocation discrimination by the local council. This led to him becoming one of the main organisers of the first Civil Rights march, from Coalisland to Dungannon on 24 August 1968. He co-founded the Social Democratic and Labour Party (SDLP) in 1970.
He became a Fine Gael TD for Dublin West in 1989. The following year, he ran for Irish presidency, coming third. He published an autobiography, 'All Hell Will Break Loose' (2004).