GWS are appealing a three-match ban handed down to Toby Bedford for tackling Richmond star Tim Taranto.
On a marathon night at the tribunal on Tuesday, Bedford and Brisbane Lions star Charlie Cameron were unsuccessful in overturning their respective rough conduct charges.
The Giants on Wednesday confirmed they will head to the AFL appeals board to challenge Bedford's suspension.
The Lions are still weighing up whether to take the same action for Cameron, who also received a three-game sanction.
During both hearings, the AFL's lawyer Lisa Hannon argued Cameron and Bedford should have released the arms of their opponents and been more careful when tackling.
"The fact Cameron's foot may've become entangled with Duggan's was entirely foreseeable and not an exceptional circumstance in a close up tackle," said Hannon, who also told Bedford he should have acted in similar fashion.
Given the strong reaction from past and current players to the bans, both clubs were always likely to give serious consideration to contesting.
Cameron's Lions teammate Josh Dunkley and Bedford's Giants captain Toby Greene both expressed their bewilderment at the respective suspensions.
"When I first saw it, I was standing next to (Richmond's) Nathan Broad and having a discussion about it, we saw the replay and thought if Tim's concussed then they might give it a week and then you'd probably challenge it," Greene told Fox Footy on Tuesday night.
"'Once he got three weeks, it doesn't seem right to me, he's making a legitimate play.
"I feel like this is overstepping the mark.
"This is a tackle that you're going to see in AFL footy for the next 50 years.
"If you eradicate this, you're just going to have to tackle standing up."
Just last week, Sydney unsuccessfully appealed against Sydney star Isaac Heeney's one-game striking ban that ruled him out of Brownlow Medal contention.
Under AFL rules, the Lions and GWS could argue there was an error of law during the tribunal hearing, that the decision was unreasonable or that the classification of the offence or sanction imposed were manifestly excessive.
Cameron will miss crucial games against ladder-leaders Sydney, Gold Coast and St Kilda as last year's grand finalists, who have won six-straight games, surge to try and secure a top-four berth.
Unless his appeal is successful, Bedford will miss GWS's matches against Gold Coast, Melbourne and Hawthorn.