... In response to a question at his prime-time news conference about the arrest of Henry Louis Gates Jr., the black Harvard professor, in his own home over the weekend, Mr. Obama declared that the Cambridge, Mass., police had “acted stupidly.” ... The police were called to Mr. Gates’s house after a report of a robbery in progress. Mr. Gates, saying he was jimmying open a damaged front door, said he told the police he lived in the house. Still, the police report said he was arrested for “loud and tumultuous behavior in a public space.” He was held in...