Johnston Withers was founded in Adelaide in 1946 by Elliot Johnston QC. Elliot was later joined by his wife Elizabeth and the firm of Johnston & Johnston practiced throughout the 1950s until Elizabeth took up a role at the Crown Law Office. They both had extensive backgrounds in Union organizations.

Throughout the 1960s, 1970s and 1980s the firm grew through its industrial work and was closely involved with numerous Unions and the Union movement generally. The firm’s areas of practice in industrial work, crime and personal injuries saw some prominent practitioners grace the firm in those years.