Generally, a dog gets two bites in California before it gets destroyed or put down. However, if you train your dog to kill, fight or attack, the law is different.
Effectively, what it means, is the "two bite" requirement of section 3342.5(b) is reduced to one bite, and any person may commence legal proceedings against the owner, if the dog has been trained to fight, attack or kill:
3342.5 (c) Whenever a dog trained to fight, attack, or kill has bitten a human being, causing substantial physical injury, any person, including the district attorney, or city attorney may bring an action against the owner of the animal to determine whether conditions of the treatment or confinement of the dog or other circumstances existing at the time of the bites have been changed so as to remove the danger to other persons presented by the animal. This action shall be brought in the county where a bite occurred. The court, after hearing, may make any order it deems appropriate to prevent the recurrence of such an incident, including, but not limited to, the removal of the animal from the area or its destruction if necessary.