The Samoa international appealed the punishment, which was meted out during the Rugby World Cup in New Zealand by tournament disciplinary chiefs.
Judicial officer Judge Jeff Blackett upheld a misconduct charge against Fuimaono-Sapolu for comments made about Welsh referee Nigel Owens during the competition via Twitter.
Fuimaono-Sapolu, who is currently serving a three-week suspension imposed by the Rugby Football Union relating to separate Twitter comments, represented himself at today's appeal hearing in London.
The three-man independent appeal committee, comprising Professor Lorne Crerar (Scotland), Graeme Mew (Canada) and Nicholas Davidson QC (New Zealand) heard submissions from the player. No new evidence was presented or new witnesses called.
The committee reserved its judgement to consider all the evidence, and expects to reach a decision within the next seven days.
At the initial hearing in Auckland, Fuimaono-Sapolu was given a six-month suspension, suspended for two years, subject to three conditions.
These were that he gives a full and unconditional apology to Owens and unconditional retraction of any criticism of him; carry out a minimum of 100 hours' rugby community work in Samoa in support of the IRB high performance programme within the next 12 months; and that the player attends and passes a recognised referee course within three months
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