Ronan O'Gara was suspended for a week following his citing for kicking Edinburgh lock Sean Cox in a Heineken Cup fixture four days ago.
The Munster and Ireland out-half will miss Munster's Heineken Pool One game against Racing on Sunday as a result, but it does not affect his availability for this season's RBS 6 Nations Championship.
O'Gara was cited following the incident at Murrayfield. He admitted the charge when he appeared at a disciplinary hearing in Dublin today in front of independent judicial officer Judge Jeff Blackett.
"The judicial officer upheld the complaint and found that O'Gara had committed a petulant act which was out of character," ERC said.
"He determined that the act was in the lower end (four weeks) of the IRB's sanctioning regime, and taking into account the player's guilty plea and his good disciplinary record, the judicial officer reduced the suspension by 50 per cent.
"Judge Blackett then determined that a two-week suspension would be wholly disproportionate to the level of offending as O'Gara had been body-checked by Sean Cox prior to the incident.
"He also accepted that O'Gara had intended to trip, rather than to kick Cox.
"As there were no aggravating factors, he imposed a suspension of one week."
Commenting afterwards, O'Gara said on the Munster website: "While I'm very disappointed that my action led to me missing this Heineken Cup game I have to say I was treated very fairly by Mr. Blackett and am very appreciative of his handling of this affair."