[1] He was born 23 January 1908 in Rockboro House, Macroom, County Cork, the son of Cornelius O'Donovan originally from Clonmel, an agricultural instructor, and his wife Hanna (née Twomey).
In 1929 he took a first class honours MA in economics and was awarded a travelling studentship, which he held at University College, Oxford, where he graduated B.Litt.
[2] In 1933 he joined the Irish civil service as an administrative officer, being assigned first to the Department of the President of the Executive Council, followed by temporary secondment to the secretariat of the League of Nations.
O'Donovan challenged the Electoral (Amendment) Act 1959, which had been passed by the Fianna Fáil government, on the basis that there were "grave inequalities" with "no relevant circumstances to justify" them.
[4] In O'Donovan v. Attorney-General (1961), the High Court held that the Act was unconstitutional and suggested that the ratio of representation to population across constituencies should differ by no more than 5%.