The 31-year-old was found guilty of two of three charges of "conduct prejudicial to the interests of the game" relating to comments made on his Twitter account - although the panel dismissed a charge that he made "insulting or provocative comments about Owen Farrell".
A guilty verdict was expected to invoke a six-month suspended sentence handed down by the International Rugby Board after he also used Twitter to criticise referee Nigel Owens during the World Cup.
And although the three-man panel instead decided only to ban Samoa centre Fuimaono-Sapolu for three weeks, they have indicated the IRB could still impose their own sanction.
"Eliota Fuimaono-Sapolu of Gloucester Rugby was tonight banned for three weeks after being found guilty of two charges of Conduct prejudicial to the interests of the Game contrary to Rule 5.12 of the Rules of the Rugby Football Union.
"The RFU disciplinary panel of Daniel White (chair), Mike Curling and John Doubleday suspended Fuimaono-Sapolu from November 8 to 28. He can play again on November 29.
"The panel found that Fuimaono-Sapolu made or adopted from other users of Twitter, critical or sarcastic comments about the rugby disciplinary process and made, or adopted from other users of Twitter, critical comments about the Rugby World Cup and the International Rugby Board on his Twitter account.
"The panel dismissed the charge of making or adopting from other users of Twitter, insulting or provocative comments about Owen Farrell, a professional rugby player, on his Twitter account.
"This finding does not necessarily trigger the suspended sentence imposed on October 15 by the International Rugby Board for breaches of the Rugby World Cup 2011/International Rugby Board Code of Conduct.
"The panel is keen to stress that this decision stands alone and that it is a matter for the IRB to determine whether the actions of Fuimaono-Sapolu constituted a breach of the conditions of that sanction."
Fuimaono-Sapolu's Gloucester contract runs out at the end of the season and the player has already indicated that should a six-month ban be handed down he would ask the club to terminate his deal.
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