Released from detention, he began to rethink his relationship with republicanism. Talking in 1968, to Tim Pat Coogan for his book The IRA, Brugha described his eventual rejection of the IRA's doctrine of the continued legitimacy of the second Dáil, saying: "We became the victims of an illusion that could never become a reality" and that "it was obvious to me that the 26 counties were politically free and that the sort of activity in which the IRA had been engaged had not helped to end Partition." Ruairí and Máire both joined Clann na Poblachta shortly after its foundation in 1946, and at the 1948 general election, he stood in the Waterford constituency which his mother had represented in the 1920s. However, the election was a disappointment for the new party, which won only ten seats, and with less than 5% of the first-preference votes, Brugha did not win a seat. Despite differences with Clann na Poblachta leader Seán MacBride — particularly over MacBride's antagonism to Fianna Fáil — he remained on the party executive during the 1950s. In 1962, he joined Fianna Fáil, and at the 1969 general election, Brugha stood unsuccessfully as a Fianna Fáil candidate in Dublin County South. He was then elected to the 12th Seanad on the Industrial and Commercial Panel, and at the 1973 general election, he won a seat in Dáil, replacing his former Fianna Fáil running mateKevin Boland, who stood for his new Aontacht Éireann party. After that election, Fine Gael and Labour formed the National Coalition government, and Fianna Fáil went into opposition for the first time in 16 years. In 1974, Jack Lynch appointed Brugha as Fianna Fáil Spokesman on Northern Ireland, where he helped reshape the party's policy and supported the Cosgrave government over the Sunningdale power-sharing agreement. After boundary changes, he lost his Dáil seat at the 1977 general election, to his party colleague, Niall Andrews. However, he was elected instead to the 14th Seanad, again on the Industrial and Commercial Panel. On the recommendation of John Hume, he was also appointed as an MEP, serving until the first direct elections to the European Parliament in 1979, when he stood unsuccessfully in the Dublin constituency. He was also active in the European Movement Ireland into his late eighties, serving as an honorary president of the organisation. Brugha did not contest the 1981 or February 1982 general elections, but at the November 1982 election he stood in Dublin South, where he polled less than 3% of the first-preference votes, and did not stand for election again.
Death
He died in Dublin on 31 January 2006, at the age of 88. On his death TaoiseachBertie Ahern said Ruairí Brugha was "a man of firm convictions who was passionate about politics and had a deep patriotic concern for the welfare of this country". He was survived by four children: Deirdre, Cathal, Traolach and Ruairí. His wife, Máire, died on 20 May 2012, aged 93. In 2006, Máire's memoir History's Daughter: A Memoir from the Only Child of Terence MacSwiney was published by O'Brien Press. It includes a detailed account of her husband's life, before and after their marriage.
