Cal. INS § 1943

A deviation is proper: (a) When caused by circumstances over which neither the master nor the owner of the ship has any control. (b) When necessary to comply with a warranty, or to avoid a peril, whether or not the peril is insured against. (c) When made in good faith and upon reasonable grounds of belief in its necessity to avoid a peril. (d) When made in good faith, for the purpose of saving human life or relieving another vessel in distress.