After the retirement of Alister McMullin, Carrick won Liberal preselection for the 1970 half-Senate election, and was elected to a term beginning on 1 July 1971. He used his maiden speech to promote a series of proposed reforms to the relationship between the federal government and the states. His second speech was given in support of Senator Lionel Murphy's private member's bill for the abolition of capital punishment, which he described as "legal murder". The bill passed the Senate but was defeated in the House of Representatives; a similar bill eventually passed in 1973. Carrick was a strong defender of the powers of the Senate, which he viewed as "the only safeguard against unbridled power and arrogance". He was one of the leading advocates for the Senate's deferral of the Whitlam Government's appropriation bills, which led to the 1975 constitutional crisis and the eventual dismissal of the government.