mrmum, do you agree that beforehand? That is, do you embark on the flight having told the 'student' that he is in command if the aircraft?
Yes, I do. I know this can be a bit contentious. I don't do it very often, I'm selective who I do this with and have to be pretty sure that they are going to fly safely. However, I accept that there's a risk they might not, then I feel the need to do something, but they are PIC and I'm just pax. Hasn't happened yet, but could be a proper can of worms.