Eddie Jones believes England captain Dylan Hartley has let himself, Northampton and his country down, but says the hooker should be allowed to "pay the penalty and get on with it".
Hartley was sent off in Northampton's Champions Cup loss on Dec. 9 for a high swinging-arm tackle on Leinster's Sean O'Brien, just six minutes after coming on as a substitute.
Jones was in the crowd at Franklin's Gardens but insists that his captain remains in contention for Six Nations selection.
"Dylan will be more disappointed than anyone about what has happened and he has got to cop the penalty, because the World Rugby directive on protecting the head is 100 percent right," he told the Telegraph.
"He has let down himself, he has let down his club and he has let down his country."
However, with Hartley's suspension ending on Jan. 23 -- 12 days before England's Six Nations opener against France -- he added that the door to selection and the captaincy remained open.
"He is eligible for selection for the Six Nations and it comes down to the case for every selection -- we pick the best 23 and if he is in the best 23, then he has a chance to be captain," he said.
"This is not the last chance for him but he understands that he can't behave in the way he did."
Speaking to The Times, Jones appeared to go even further. "Dylan makes one bad decision in a tackle choice and now he is the greatest dunce in English rugby," he said.
"It is quite incredible. Dylan loves playing for his country. Let him pay the penalty and get on with it."
Press Association Sport contributed to this report