He was an MP in two separate spells and a member of two different governments, including being a minister in the latter where he reformed the country's justice system.

He used to push his brother Harold, ten years older and with polio, two miles to Otago University in his wheelchair.

[3] He returned to NZ in 1939 and was employed as a private secretary to Cabinet Ministers Rex Mason and Arnold Nordmeyer.

Finlay frequently challenged Prime Minister Peter Fraser in caucus over issues such as compulsory military training, earning him the ire of the party establishment.

After his defeat neither Fraser nor his successor as leader Walter Nash gave Finlay any assistance in returning to parliament because of his rebelliousness.

[5] He stood for the Labour nomination at the 1953 Onehunga by-election but lost out to the comparatively inexperienced candidate Hugh Watt.

When the United States Vice President Spiro Agnew visited the capital Wellington in mid-January 1970, Finlay along with several other Labour Members of Parliament including Arthur Faulkner, Jonathan Hunt, and Bob Tizard boycotted the state dinner to protest American policy in Vietnam.

However, other Labour MPs including the Opposition Leader Norman Kirk attended the function which dealt with the Nixon Doctrine.

[21] The same year he was a member of the legal team that represented the New Zealand and Australian government at the International Court of Justice in an attempt to ban French nuclear tests in the Pacific.

[22] Finlay attracted world-wide attention with his performance leading the New Zealand team at the World Court in the joint New Zealand-Australia case seeking a ban on French nuclear testing at Mururoa Atoll.

He set up the Disputes Tribunal and was responsible for much of the work leading to the Matrimonial Property Act which would give divorced wives a right to share in their husband's possessions.

[20] Prior to announcing his retirement it was speculated in 1976 that he would leave parliament mid-term to cause a by-election which Labour would use to test public mood ahead of the general election.

[4] In 1983 his daughter Sarah Jane was sentenced to nine months' imprisonment on charges of supplying and possessing heroin.

[20] Finlay's socially liberal views were said to have put him ahead of his time, especially on moral issues such as legalizing homosexuality and granting name suppression in court unless people were convicted.

[8] Parliamentary colleague Michael Bassett has said Finlay was "essentially a man of peace throughout his life" who "found Peter Fraser's crusade to introduce Compulsory Military Training personally distasteful.

Finlay’s reputation as an advanced liberal on social issues attracted the support of younger party idealists as much as it repelled Labour's more conservative wing, especially Catholics.

Finlay’s marital complications irked the puritanical Walter Nash, who did nothing to advance his return to Parliament, and seems not to have welcomed his election as party president in 1960.