Neglecting or refusing to fulfill a promise, this may be the basis for a law suit if it has caused a person harm.  Judicial decisions have labeled ‘bad faith’ as the following: concealment; fraud; evasion of the spirit of the bargain; lack of diligence or slacking off; willful rendering of imperfect performance; abuse of a power to specify terms; and interference with or failure to cooperate in the other party’s performance.