Mackay was initially referred directly to the tribunal without a specific charge when the match review findings were released on Sunday.

The AFL on Monday confirmed that decision was made by the league's executive general manager of football, Steve Hocking, who exercised his right to make a ruling over the top of match review officer Michael Christian.

Mackay's tribunal hearing has been set for Thursday, with Adelaide having a bye in round 14.

Under instruction from the AFL, the league's legal counsel will allege that Mackay carelessly engaged in rough conduct that was "unreasonable in the circumstances" when he collided with St Kilda's Clark during Saturday night's match in Cairns.

"As such, the AFL will argue that, regardless of whether player Mackay was (1) contesting the ball, (2) bumping player Clark or (3) both, he still contravened the general prohibition on unreasonable conduct (including in contesting the ball)," the league said in a statement.

As well as careless conduct, the league will also contend there was high contact and severe impact caused by Mackay.

Those gradings would usually result in a minimum three-match ban under the AFL tribunal guidelines.

"The AFL will submit that, assuming the tribunal determines that it was careless conduct/high contact/severe impact, that a suspension of at least three matches is appropriate," the league's statement said.

"The AFL will, if necessary, make further submissions on penalty at the tribunal."

Hocking's decision to send Mackay to the tribunal has split opinion among AFL experts and fans.

Many former players have claimed the incident was purely a football accident that should go unpunished because both players were trying to win the ball.

"There will be times when players need to slow up ... I think in this instance the ball is still there to be won," Melbourne great Garry Lyon told SEN.

"You can't say don't go fast when the ball is in dispute."

But former North Melbourne star David King said he would support a suspension because Mackay made a decision that was likely to result in significant contact.

"I'm looking at the health and wellbeing of players long-term," King told on Fox Footy.

"We've got so many players on the sidelines with their lives being altered at 21-22 years of age.

"They've got 80 years of their lives to come."

Hawthorn's Jaeger O'Meara and Gold Coast's Jarrod Harbrow were cleared of wrongdoing in separate similar incidents earlier in the season.

Mackay's case will now act as a test case for future head-high collisions.

Australian Associated Press