Reservations are essentially caveats to a state's acceptance of a treaty. Reservations are unilateral statements purporting to exclude or to modify the legal obligation and its effects on the reserving state. These must be included <answer>at the time of signing or ratification</answer>, i.e. "a party cannot add a reservation after it has already joined a treaty".
When must reservations be included in a treaty?
at the time of signing or ratification