Principle : A citizen is expected to take reasonable duty of care while driving on the road and not to cause injuries to any person.
Facts : X, the owner of a car, asked his friend Y to drive the car to his office. As the car was near his (X's) office, it hit a pedestrian P on account 'Y's negligent driving and injured him seriously. P sued X for damages.
Two persons are said to be joint tort-feasors when ______________.