Summary: As the campaigns look ahead, Mitt Romney targets Barack Obama, but he is targeting youth voters. The Supreme Court hears arguments on Arizona immigration law. Also, a year after Osama bin Laden's death, balancing terrorism and civil liberties. Joining Gwen: John Dickerson, Slate Magazine/CBS News; Alexis Simendinger, RealClearPolitics; Pete Williams, NBC News; James Kitfield, National Journal.
