Nathan Hughes has had his ban for kneeing George North in the head quashed after RFU disciplinary bosses reversed their decision in what could become a landmark judgement.
Wasps number eight Hughes was sent off by referee Craig Maxwell-Keys for colliding with North as the Wales wing scored a try in Wasps' 52-30 defeat to Northampton on March 27.
Sir James Dingemans, the RFU's head of independent rugby judiciary, then imposed a three-week suspension, claiming "recklessness" trumped any lack of intention on Hughes' part.
In Friday night's appeal however, hearing panel chairman Jeremy Summers overturned that decision and rescinded Hughes' red card, ruling "no act of foul play took place in that the incident occurred accidentally".
Summers claimed the appeal committee "had the advantage of evidence not before the original panel", but such an about-turn is extremely rare.
"As a club, we feel we have a duty not only to protect player welfare, but also to protect the reputation of players who we feel have been unfairly sanctioned," said Wasps' rugby director Dai Young.
"We strongly believed this incident was an accident and that is why we appealed.
"We are delighted for Nathan that he has had the red card dismissed. He is a good guy, who has always had a clean record and I am pleased for him that that remains."
Wales wing North was concussed in the incident and subsequently stood down for a month by neurologists, while Wasps launched an immediate appeal against Hughes' ban.
Neutral observers have suggested the manner of North's injury coloured both referee Maxwell-Keys' decision to send off Hughes and the Fiji-born number eight's subsequent suspension.
Fears were raised about the viability of full-blooded tackles as a result of the decision - but this reversal suggests that rugby can continue with its status quo.
Hughes' initial ban meant he was forced to miss Wasps' Champions Cup quarter-final clash at Toulon on Sunday, that Young's side lost 32-18.
Rugby director Young kept his counsel but will no doubt have been frustrated to lose one of his key ball-carriers for the biggest match of Wasps' season.
"The appeal panel considered it appropriate to hear the matter afresh," said Summers.
"Having done so and having had the advantage of evidence not before the original panel, it concluded that no act of foul play took place in that the incident occurred accidentally."
Hughes is now free to play immediately, though will sit out Wasps' Premiership clash with already-relegated London Welsh on Saturday.
Wasps named their team at midday on Friday in adhering to league regulations, at which point Hughes was still banned.
Hughes' overturned ban will be a huge boost to Wasps' bid to cement a top-six finish however, with clashes against Exeter, Leicester and London Irish still to come.
"We are thrilled to be able to welcome Nathan back to the squad," said Wasps boss Young.
"The team has already been selected and announced for London Welsh this Sunday, but to have him available for Exeter Chiefs on April 26 is a huge boost for the squad and our supporters."