When Professor Cass Sunstein was a young law professor, he happened to come across an older male professor talking to a young female student in a hallway. To his astonishment, the professor was stroking the student's hair.

Prof Sunstein later went up to her and said: "That was completely inappropriate. He shouldn't have done that." The student brushed him off: "It's fine. He's an old man. It's really not a problem." Thirty minutes later the same student appeared in his office, in tears. "He does that all the time," she cried out. "It's horrible. My boyfriend thinks I should make a formal complaint, but I don't want to do that... I don't want to make a fuss."