As Minister of Justice, it was Hanan's role to introduce the legislation to Parliament, but he convinced enough of his party colleagues to vote with the opposition and thus abolished the death penalty in New Zealand.

[8][9] In 1961, Hanan and nine other National MPs (Ernest Aderman, Gordon Grieve, Duncan MacIntyre, Robert Muldoon, Lorrie Pickering, Logan Sloane, Brian Talboys, Esme Tombleson and Bert Walker) crossed the floor and voted with Labour to abolish the death penalty for murder in New Zealand.

[2] He convinced enough of his party colleagues to vote with the opposition and thus abolished the death penalty in New Zealand, which is what he is best remembered for.

On many occasions, he developed policy that was initially not accepted by his party colleagues, but he managed to talk them round to it.

[2] One controversial piece of legislation that he introduced was the Maori Affairs Amendment Act 1967, which was bitterly opposed by many Māori, as they feared that it would lead to further loss of land.

When two of the inner circle, Hanan and Tom Shand (Minister of Labour), died within months of one another, Holyoake's strong position was weakened.

[12] Hanan died on 24 July 1969, aged 60, after attending the annual conference of state attorneys general in Brisbane.

The Niue International Airport is named after Hanan, having been constructed during his tenure as Minister of Island Affairs (1963–1969).