It was at this time that his most prominent moment as a lawyer occurred, representing the miners before the Royal Commission into the Mount Kembla mining disaster.

[2] Lysaght entered state politics in 1925, when he defeated incumbent Nationalist Mark Morton for the final seat in multi-member Wollondilly.

In 1927, following the abolition of the multi-member system, he contested and won the recreated seat of Illawarra, defeating sitting MLA Brian Doe.

[4] A redistribution of the region in 1930 saw him contest and win the new seat of Bulli,[5] and Lang's return to power saw him again appointed Attorney-General, despite lacking support within the Labor caucus.

He clashed heavily with ideological rivals within Labor, and slowly lost Lang's support; he had also become increasingly irascible, associated with his declining health as a result of a disease of the nervous system.