Uncooperative Professor
You interpret in a college course where you're convinced that the professor hates all people, especially interpreters. Today he's showing some slides in class and so he turns off the lights. When the Deaf student asks for some kind of compromise for a light source, the professor steadfastly refuses the student's request.
An Interpreter's Perspective:
This is a tough one. RID frowns upon the appearance of paternalism, and taking up the cause for this consumer would definitely be that. However, you could offer to interpret the student's complaint to the disabled students' office.
A Deaf Consumer's Perspective:
Follow the lead of the Deaf student. If the student wants to make a formal complaint, go with the student to facilitate that communication.