GEELONG star Tom Stewart has been suspended for four matches by the AFL Tribunal on Tuesday night.

After 45 minutes of evidence and 30 minutes of deliberation over Stewart's bump on Richmond's Dion Prestia, Tribunal chair Jeff Gleeson delivered the news the defender and the Cats had been dreading.

RECAP Tom Stewart's Tribunal case as it happened

"The bump was late," Gleeson said.

"He (Prestia) was wide open, exposed and vulnerable.

"Stewart had sufficient time to see Prestia had not taken possession (of the ball).

"He ran past the ball and made a conscious, albeit split-second, decision to bump Prestia at speed.

"The degree of carelessness was high.

"He breached his duty of care by some margin."

The incident that left Prestia concussed happened early in Saturday's thrilling match at the MCG and was assessed by the AFL's Match Review Officer as careless conduct, severe impact and high contact. 

The boundary lines for Tuesday night's hearing were drawn early, with the AFL arguing it wanted Stewart suspended for four weeks and Geelong counsel Ben Ihle arguing for three weeks.

AFL counsel Nicholas Pane said it was a simple matter of Stewart running past the ball and putting Prestia in a "vulnerable position" – a premise the Tribunal ultimately sided with.

"The injury suffered by Prestia, concussion, is a serious injury in itself," Pane said.

"It's the very type of action which can cause (even more) serious injury."

He said AFL players were now well educated on concussion and the impact it could have long-term.

Stewart attended the Webex hearing but did not give evidence.

That was left to his representative Ihle, who conceded the three-time All-Australian chose to bump, but had just 0.39sec to make a decision after Prestia tapped the ball on.

He also argued Stewart's character and the defender's remorse for his actions should have been considered in giving a lesser sanction. Gleeson said Stewart's character was considered in the final verdict.

"He made the wrong decision, but it was less than half a second," Ihle said.

"He has expressed his genuine concern for Prestia and his genuine disappointment in that split-second decision that he made because it's something out of character.

"The remorse was immediate and resounding."

Geelong used two 2021 incidents to push Stewart's case for a lighter sentence – Giant Sam Reid's bump on Nat Fyfe that landed him two weeks, and Patrick Dangerfield's bump on Jake Kelly that landed him three.

Stewart will miss matches against North Melbourne, Melbourne, Carlton and Port Adelaide.