As with discussions of sensitive topics, the best defense against problems students and disruptive behavior is to be prepared.
Handling Specific Disruptive Behaviors is an excellent article that provides concrete suggestions for college faculty. Talking in class, packing up early, arriving late/leaving early, cheating, wasting time, asking problematic questions, showing disrespect, attending class irregularly, asking for extension and missing assignment deadlines are all covered here.
It is your right to expel a disruptive student from your classroom--but only for that day's session. The student has the right to return to class the following day, and may remain so long as the disruptive behavior is not repeated.
At a recent meeting of Berkeley faculty to discuss this issue, the group had several excellent recommendations:
1. Always make deadlines--and consequences of missing them--clear in the syllabus. And then stick to them. Some faculty also include expectations for classroom behavior.
2. Know your rights and responsibilities as outlined in the Faculty Code of Conduct. Know students' responsibilities as outlined in the Student Code of Conduct.
3. In serious cases, rely on your department chair for support and advice. That's what the chair gets paid for.
4. You do NOT need to respond to a demanding student email.
5. If you wish to respond to an email, you can say, "I looked at this briefly, and it looks important. Please come to my office hours." The group agreed that this eliminates 50% of complaints, because, as one student told a professor, "It's not worth the trouble to go to office hours."
6. In severe cases, keep written records (including all email, etc.)
7. In general, don't correct or criticize students in class; talk to them privately after class, if necessary.
8. Think in advance how you might respond to various behaviors so that you'll not be blind-sided and can remain calm.