A graduate of University College Dublin , Ó Dálaigh was a committed Fianna Fáil supporter who served on the party 's National Executive in the 1930s , he became Ireland 's youngest Attorney General in 1946 under Taoiseach Éamon de Valera , serving until 1948 .
He became Ireland 's youngest Attorney-General in 1946 under Taoiseach Éamon de Valera .