Following the decision by Boston College to bar a planned speech Monday by William Ayers, students instead devoted the day to talking about academic freedom. College officials said that they called off the Ayers event  because of the sensitivity in Boston to a 1970 police killing that, while not viewed by experts as linked to the Weather Underground, is associated with the Weather Underground by some residents and by many conservatives on talk radio. Ayers, a University of Illinois at Chicago professor, was once a leader of the Weather Underground. The Massachusetts chapter of the American Civil Liberties Union was among the groups that on Monday condemned the college's actions. A letter from the ACLU charged that the college has "abandoned its own mission statement, which expresses a firm commitment to academic freedom."