Richmond defender Nathan Broad has received a four-match suspension from the AFL Tribunal on Tuesday night.

Match Review Officer Michael Christian charged Broad with rough conduct for the tackle, which was graded as careless conduct, severe impact with high contact.

In 50 minutes of evidence, the AFL pushed for the lengthy ban, saying the tackle was "moving towards a higher grading of severity" and compared it to a four-week suspension suffered by Scott Lycett in 2021 for a similar tackle on Ned McHenry.

The AFL said aside from Parnell's concussion, there was further potential to cause injury.

Broad pleaded guilty, with his counsel Sam Tovey asking for leniency and a three-week ban due to his "good character".

But the Tribunal decided the offence was serious enough to warrant four games, with chairman Jeff Gleeson offering a warning to all players.

"We repeat tonight, players must do all they reasonable can not to cause avoidable head injuries to fellow players," Gleeson said.

"Every player is now taken to be aware of the damaging and sometimes long-term consequences of concussion.

"If not for the early guilty plea to all elements of the charge and the clear contrition (shown by Broad), our starting point for the sanction may have been more than four matches, but taking into account all the circumstances I've mentioned, we start with a base sanction of four matches."

Tovey pushed hard for the suspension to remain at three weeks, saying that although the tackle was "self-evidently harmful", the three-time premiership Tiger showed genuine remorse and had not been banned in 110 AFL and 45 WAFL games.

He said from the moment the incident happened, Broad showed his care, immediately telling opponent Darcy Fogarty he shouldn't have done it, apologising to Adelaide coach Matthew Nicks, and then sending Parnell a text.

"I don't want you to accept my apology, but I shouldn't have done it," the text read.

"Sorry mate. It was sh*thouse. I hope you're ok and recover well."

Tovey said it was not the same as Lycett's tackle on Crow Ned McHenry in 2021, which earned the Port ruckman a four-week suspension.

Richmond argued Broad was spinning Parnell to take him over the boundary line, whereas Lycett's was in open play and he deliberately tossed the Crow over his shoulder and into the ground.

Broad will miss matches against Collingwood, Western Bulldogs, Sydney and Melbourne.