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.

[5] After that election, Fine Gael and Labour formed the National Coalition government led by Liam Cosgrave, 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's position in favour of the Sunningdale Agreement.

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.

[6] On his death Taoiseach Bertie 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".