Livingstone was suspended from office last month, one year after he compared Jewish Evening Standard reporter, Oliver Finegold, to a Nazi concentration camp guard.
The mayor's four-week suspension was later postponed while he fights the ruling by the Adjudication Panel for England, which followed an investigation by the Standards Board for England.
The case began after a complaint from the Jewish Board of Deputies about the comment made by Livingstone in February 2005.
Livingstone was annoyed that Finegold had approached him as he left a party and asked the reporter if he was a "German war criminal".
Finegold told him he was offended and Livingstone said: "Well you might be, but actually you are just like a concentration camp guard, you are just doing it because you are paid to, aren't you?"
The mayor, who refused to apologise for his comments, said after the ruling: "I believe what I said was right. I said it to many journalists. No one has ever complained before."
Sir Anthony Holland, chair of the Standards Board for England, said: "The public expects all elected members to conduct themselves in a manner that is beyond reproach.
"It is right that the facts of this case have been aired and considered in this way."
The cost of the Standards Board for England's case has amounted to around £45,000, while the Adjudication Panel's costs are around £7,000.
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