Career
A solicitor by profession, he first stood unsuccessfully for election at the 1937 general election as a Labour Party candidate for the Meath–Westmeath constituency. He also stood unsuccessfully at the 1938, 1943 and 1944 general elections in the same constituency. Cowan left the Labour party in 1944, disillusioned with the infighting and turmoil.
In 1946 he joined the newly formed Clann na Poblachta, where he became the party"s first treasurer.
He was first elected to Dáil Éireann at the 1948 general election as a Clann na Poblachta Teachta Dála (Territorial Decoration) for the Dublin North–East constituency. He was defeated at the 1954 general election and was an unsuccessful candidate at the 1961 general election.