Illinois of course prohibits people under 21 from drinking alcohol. Except that it's permitted "in the performance of a religious ceremony or service." Students attending ostensibly religious functions (a.k.a. "parties") at the Tannenbaum Chabad house at Northwestern University did indeed consume alcohol there -- so much, in fact, that one student had to be hospitalized for excessive consumption.
A discrimination suit against the university arose after Chabad's advisor, Rabbi Klein, failed to make any changes to the house, resulting in the university "disaffiliating" itself from Chabad and barring Klein from contracting with a food company called Sodexo to provide rabbinic supervision over its kosher food.