In fact, according to the National Rifle Association, at least 30 states have some form of legislation protecting people from prosecution when they feel threatened by intruders to their property. In New Hampshire last year, legislators overrode Governor John Lynch's veto when he objected to a castle doctrine bill that allows anyone to defend themselves if they are in their "dwelling, its curtilage, or anywhere he or she has the right to be." Governor Lynch said the new provisions would increase "deadly violence," but the legislature disagreed.
The year 2011 was a successful one for the castle doctrine in many parts of the country, with states enacting new laws and, as in New Hampshire, expanding earlier ones. In December, Wisconsin Governor Scott Walker signed a bill expanding the castle doctrine to include a person's right to use deadly or substantial force against someone who unlawfully and forcibly enters their "dwelling," "vehicle," or "place of business," which Walker said would "deter future criminal intrusions as well as provide added legal protections for those who use force to protect their home or property."
The Wisconsin State Bar Association, state prosecutors and state police were all opposed to the bill. In a memo to all assembly members, Gregory O'Meara, a past chair of the state bar's criminal law section, wrote that the bill "changes Wisconsin law by providing a defense for irrational people armed with deadly force. Under its provisions, malevolent, reckless, or paranoid people who shoot trick-or-treaters or repairmen on their porch will be presumed to be acting in self-defense."
At the national level, the Association of Prosecuting Attorneys argues that the right of self-defense and defense of property are well established in common law and don't need to be legislated. They also worry that the laws create a presumption of innocence for the shooter, rather than encouraging prosecutors to use their discretion to decide how to proceed with a case.
Meanwhile, the National Rifle Association is advocating for castle doctrine laws in the 20 states that don't have them, so that, in the words of NRA spokeswoman Stephanie Samford, "the law does not put victims in a place where they have to defend themselves against legal prosecution."
While the laws do give a presumption of innocence to the castle doctrine shooter, police and prosecutors must still investigate and decide whether to file charges. In the McKinley case in Oklahoma, prosecutors have said they will not file charges in the shooting.