All this week, President Obama has been talking about racial inequality in this country's criminal justice system. Yesterday, he became the first sitting president to visit a federal prison. On Tuesday, President Obama spoke passionately before the NAACP's annual convention about the need for reform. The president's rhetoric on race has changed since his first years in office. For some insights on this, we turned to political science professor Lester Spence of Johns Hopkins University. Our conversation began with an incident six months after Obama's inauguration. Harvard professor Henry Louis Gates, who's black, was arrested by a white policeman while trying to enter his home. Spence reminded us how the president responded.

LESTER SPENCE: He ends up reconciling the whole event with a beer summit. He brings Henry Louis Gates and the officer to the White House for beer. And that's - one way to read that is that's his politics. It's the politics of consensus building, right? It's the idea that the primary problem black people face with the police is a problem of understanding.

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