For the last few years, I have been including the following language in my syllabi:
Firearms Policy: I do not allow firearms in my classroom. (I will consider exceptions for on-duty law enforcement officers.) This policy is irrespective of federal, state, county, and city laws and system, university, college, department, and program policies. Failure to abide by this policy may result in immediate expulsion from the classroom and a failing grade in the course.
It is an embarrassment to our nation that I feel compelled to do this.