Because some student demonstrations protesting his scheduled appearance have resulted in violence, the president of the Imperialist Society has been prevented from speaking about politics on campus by the dean of student affairs  Yet to deny anyone the unrestricted freedom to speak is to threaten everyone' s right to free expression
Hence, the dean' s decision has threatened everyone' s right to free expression
Fire fighters are often expected to perform heroically under harsh conditions. But no one is ever required to act heroically. Hence, fire fighters are often expected to perform actions they are not required to perform.