Race row after arrest of professor

Have you heard the one about the president, the professor and the policeman?

The issue of race in the US is alive and kicking as the case of the arrest of a Harvard professor last week has highlighted.

Professor Henry Louis Gates Jr was arrested at his home after he was seen trying to force his way in to the house.

He was held for disorderly conduct after allegedly accusing the arresting officer, Sgt James Crowley, of racism.

President Obama used up political capital as he got involved in the case, saying that the police had acted "stupidily".

Things have now changed to such an extent that Sgt Crowley is being invited to the White House for a beer.