World Rugby has come under pressure to act after Owen Farrell's red card against Wales was overturned in a decision that has caused uproar across the game.
Farrell was sent off in the second half of Saturday's 19-17 victory at Twickenham after his yellow card for a shoulder-led tackle to the head of Taine Basham was upgraded to a red by the bunker review system.
While the England captain was expected to face a ban that would rule him out of the start of the World Cup, a disciplinary hearing instead concluded that the offence was worthy of a sin-binning only, clearing him to play.
The hearing decided that a "late change in dynamics" due to Jamie George's involvement in the contact area "brought about a sudden and significant change in direction from the ball carrier".
Six Nations, who oversee the warm-up fixtures, have a policy of not publishing full written judgements, but are facing calls to make the detailed reasoning behind the independent panel’s decision public.
They have the power to appeal the verdict and so do World Rugby, who will examine the report before making a decision.
Progressive Rugby, a player welfare lobby group, believe the sport’s global governing body must intervene.
"World Rugby must emerge from its corporate bubble of stakeholder management and delegated responsibility to bare its teeth," Progressive Rugby said on Twitter.
"For it to demonstrate it WON’T stand still on player welfare, that it IS the game’s number one priority and that they won’t tolerate being undermined."
Ireland host England in a World Cup warm-up game in Dublin on Saturday (5.30pm).
Meanwhile, loose-forward Basham was named on the Wales bench for their game against South Africa this weekend.
He failed a head injury assessment after clattering into the shoulder of attempted tackler Farrell, though no symptoms of concussion were later found by the Wales medical team.
A stringent three stage protocol was followed and Basham was given the all-clear this week.
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