Intersting point but it would be the rules of the air that would decide it not the fact that one is in the circuit and one is joining.
Arguably quite so. In the OHJ situation, it could be argued that a joining aircraft is attempting to overtake one established in the pattern and climbing to circuit height. The joining pilot must therefore overtake on the right, i.e. for the normal left hand circuit, pass further upwind.
znww5,
The other aircraft joining, had he been aware of your presence, had two options. He could have either stopped his descent to circuit height and continued circling to space behind you, or he could have slackened his turn to pass behind you, which would have meant he merely had a slightly longer downwind leg. He obviously didn't consider either, effectively leaving you no option but to leave the circuit by climbing above the height of the pattern. Poor airmanship on his part.