Williams used a blood capsule to fake a blood injury against Leinster
European Rugby Cup will not take any further action against Harlequins over the damaging 'Bloodgate' scandal.
The organisers of the Heineken Cup say misconduct charges against the club and its staff have been brought "as far as is feasible in this instance".
Quins were fined £259,000 while boss Dean Richards, winger Tom Williams and physio Steph Brennan were handed bans for their roles in the affair.
The Rugby Football Union (RFU) must now decide whether it will take any action.
In a statement issued shortly after Tuesday's ERC judgment, the RFU said that disciplinary officer Jeff Blackett will decide by 1700 BST on Friday whether to act.
If he rules that Quins are guilty of conduct prejudicial to the interests of the game or the RFU - on any issues not dealt with by the ERC - then the London club could face further punishment.
Former Quins rugby director Richards was banned for three years, Brennan received a two-year punishment and Williams landed a four-month suspension following the 'Bloodgate' saga and subsequent attempted cover-up.
The bans, imposed by an ERC independent appeals committee, followed last season's Heineken Cup quarter-final between Quins and Leinster when Williams bit on a fake blood capsule as Richards attempted to get goalkicker Nick Evans back on the field to try and win a game Quins eventually lost 6-5.
The ERC plan to send the RFU evidence to help its inquiry into the London club's conduct.
"The ERC disciplinary officer has brought the misconduct charges against Harlequins and/or its officials and staff as far as is feasible in this instance," said an ERC statement.
"The board has directed the ERC disciplinary officer to pass onto the RFU, where appropriate, relevant information gathered in ERC's investigation and hearings."
ERC also revealed they had been contacted by the General Medical Council seeking information regarding Dr Wendy Chapman's involvement in the disciplinary process.
Chapman was Quins' match-day doctor for the Leinster game.
In his evidence to the appeals hearing in Glasgow last month, Williams alleged that Chapman - at his suggestion - agreed to cut his lip as part of the injury cover-up.
ERC added: "The board have reserved their position in relation to Dr Wendy Chapman."
Quins, as confirmed by ERC last week, will play in this season's Heineken Cup competition.
Their opening pool game is against Cardiff Blues on 10 October.