Neurosurgeon Dr. Ben Carson stepped down Wednesday as commencement speaker at the Johns Hopkins School of Medicine after complaints from students about controversial comments concerning same-sex marriage. The withdrawal came less than a week after medical school Dean Paul B. Rothman chastised Carson for his comments and met with graduating students concerned that the famed physician was an inappropriate commencement speaker. Carson sent Rothman a letter saying that he didn't want to "distract from the celebratory nature of the day."