I'm a grad student who will be teaching a course for the first time over the summer, and I'm not sure what the convention is on allowing a student to "sit in" on the class (that is, attend class without being registered, not getting credits, etc). If a student asks before class for permission to do so, is it to my discretion on whether or not to allow it? I suppose it's always within the instructor's right to deny the request, but it seems like approving the request without the school's permission could be a mistake, since I am an employee of the university. The faculty handbook seems to only consider if the student audits the course, in which case they have to officially register as auditing the class, but nothing about unofficially sitting in. Am I extending past my right as instructor if I let a student sit in?
EDIT: This is at a private university in the US.