He was first nominated to fill the casual vacancy caused by the resignation of Don Grimes in April 1987. However, his nomination was rejected by a tied vote in the Tasmanian Parliament. but we are not bound to accept the nomination of the party concerned". Following a double dissolution of the Commonwealth Parliament, he was elected at the election of 11 July 1987.
From 24 to 27 January 1994, thirty protesters from the Tasmanian Wilderness Society (TWS) blockaded Riveaux Road in the Picton Valley in Tasmania to prevent logging of woodland.
The then Tasmanian Premier, Ray Groom, and Tasmanian Forestry Commission Chief, Bob Gordon, claimed that the adjacent wilderness forests were not old-growth, but re-growth, because a wildfire went through the area approximately 100 years ago. At the blockade, Senator Devereux announced his resignation from the ALP in protest against its policies on forest issues.
Devereux served out the rest of his term, from 1994 until 1996, as an independent Senator. He is currently the Chief Executive Officer of the Tasmanian Pacing Club.