Governor Granholm has signed legislation that supporters say will strengthen and clarify self-defense rights in Michigan.
People now will be allowed to use deadly force with no duty to retreat if they reasonably think they face imminent death, great bodily harm or sexual assault.
The law also protects people from civil lawsuits if they have used force in self-defense.
Critics say the law is not only dangerous but also unnecessary because prosecutors already don't charge people who have justifiably used deadly force to protect themselves.
Supporters say the law is needed to protect people from getting sued and partly because Michigan law previously required people to first retreat before using deadly force, putting them at a disadvantage.