Speight will miss Saturday night's semi-final against the Hurricanes in Wellington, the final if the Brumbies qualify and the first two games of Australia's Rugby Championship campaign against South Africa and Argentina.

A SANZAR judicial hearing on Tuesday found that Speight was guilty of a lifting tackle in last weekend's 39-19 win in the qualifying final against the Stormers in Cape Town.

However, the judicial officer, Robert Stelzner SC, requested further information be presented for consideration before a sanction was handed down on Wednesday.

Utility Robbie Coleman is the most likely option to come on to the wing to replace Speight, while rookie James Dargaville and Nigel Ah Wong are the other candidates.

A Brumbies spokesman said the club wouldn't be commenting on Speight's suspension.

The tackle was at the lower end of the scale which stipulates a four-week ban.

Stelzner added an additional two weeks as a deterrent for dangerous play, while removing two weeks for Speight's unblemished disciplinary record.

Another week was added when Speight's upcoming schedule was taken into account given he will have a rest week when no game is played.

Speight was handed a red card in the 74th minute of the win against the Stormers when he appeared to flip Juan de Jongh on to his head when he didn't have the ball.

"As the judicial officer, I considered all the evidence before me including the video footage of the incident, referee and TMO reports for issuing the red card and the submissions made for the player by his legal representative, Peter McGrath," Stelzner said.

"After taking all relevant facts into consideration, I found that the referee's decision to issue a red card was correct.

"It was submitted on Speight's behalf that the tackle was part of a legitimate attempt to clear Juan de Jongh from a ruck.

"The player tackled his opponent before De Jongh had joined the ruck.

"In my assessment, Speight did so in response to De Jongh impeding his access to the breakdown and joining the ruck which had been formed.

"The dominant movement of his right arm, the positioning of his leg under De Jongh and that of his left hand behind De Jongh's neck together with Speight's driving movement on to De Jongh, caused the player to make contact with the ground, head first, in a cartwheel movement.

"At the moment of impact with the ground, De Jongh's feet had been raised off the ground by Speight which constituted dangerous play in contravention of Law 10.4(j)."

Speaking before the judiciary hearing on Tuesday, Brumbies coach Stephen Larkham said he had several contingences in place if Speight was ruled out.

"We've got Robbie Coleman, James Dargaville and Nigel Ah Wong, all have had really good years this year," Larkham said.

"All have very good combinations with the other starting members.

"Whichever way we go there we'll be fine."