England hooker Dylan Hartley has been banned for eight weeks after being found guilty of biting.
But the length of the ban means the Northampton forward will be available for England's three-Test tour of South Africa in June.
Hartley was cited following an incident with Ireland's Stephen Ferris during England's 30-9 Six Nations win at Twickenham on March 17 after a disciplinary panel found that he had contravened International Rugby Board Law 10.4(m) "acts contrary to good sportsmanship''.
The panel heard evidence from back-row forward Ferris, via video link, as well as Northampton director of rugby Jim Mallinder and England forwards coach Graham Rowntree.
In upholding the citing for foul play, the panel, chaired by Roger Morris of Wales, decided the offence merited a low entry point in the IRB's table of sanctions and allowed mitigation of four weeks.
A biting offence carries a low-end entry point of a 12-week suspension, with 18 weeks for mid-range and 24-plus weeks at the top end.
New Zealand-born Hartley, 25, is free to play again on May 14 and he has the right of appeal.
Ferris was heard accusing an England player of biting during the match.
Biting is a red card offence but as neither referee Nigel Owens nor his touch judges saw the incident, no action was taken during the game.
Owens, in a conversation recorded on his microphone in the 28th minute, told England captain Chris Robshaw and Ireland skipper Rory Best: "I have an accusation of biting, a clear mark on the finger.
"I did not see something ... It could be dealt with afterwards.''
England's victory saw them finish second in the tournament, with Ireland in third place.