He introduced electoral reform, removing the Playmander which favoured the Liberal and Country League, which contributed to his party's loss at the 1970 South Australian state election.

He continued as a state parliamentarian until he resigned his seat in 1974 to be the Liberal Movement's lead Senate candidate at the 1974 Australian federal election.

Quickly gaining a reputation for his independence and strength of his views, Hall rose through the Liberal and Country League parliamentary ranks to assume party leadership following Premier Thomas Playford's retirement in July 1966.

Although Hall was considerably more progressive than Playford, the two men shared a background as small farmers, rather than members of the rural elite or the Adelaide Establishment.

Deliberately inequitable electoral boundaries, commonly known as the Playmander, had greatly advantaged the Liberal and Country League over the past 40 years.

Hall sponsored an electoral reform Bill which expanded the House of Assembly to 47 seats, including 28 in the Adelaide area.

In addition to electoral reform, Hall also introduced improvements in social welfare, Aboriginal affairs and abortion regulation.

Hall remained Leader of the Opposition for two years before resigning from the Liberal and Country League on 15 March 1972, claiming that the party had 'lost its idealism [and] forgotten...its purpose for existence'.

Hall and his fellow Liberal Movement members helped the Dunstan Government introduce adult suffrage and proportional representation for Legislative Council of South Australia elections.

[1] After much of his base was transferred to the Yorke Peninsula-based seat of Goyder before the 1973 state election, Hall ran as the Liberal Movement candidate there and won.

At the Joint Sitting of Parliament, Hall supported the Labor government's three electoral reform Bills, citing his experience as South Australian Premier.

[3] During the 1975 Australian constitutional crisis, though opposed to the Whitlam government, Hall joined Labor (and independent Cleaver Bunton) in voting against the deferral of supply bills.

In August 1988, after the then opposition leader John Howard expressed his wish to control Asian immigration in Australia,[6][7][8][9] Steele Hall (along with Ian Macphee and Philip Ruddock) dissented by crossing the floor of parliament and voting with the Labor government on a motion against the use of race as a criterion for selecting immigrants.

However, he returned to the backbench in 1984, where he remained for the remainder of his parliamentary career including when fellow South Australian Alexander Downer became leader in 1994.