In Scottsdale, Arizona, any new home must come equipped with fire sprinklers, a decades-old rule lauded by fire safety advocates nationwide. But 12 miles away in Phoenix, city officials are not even allowed to discuss adopting a requirement like Scottsdale's, because of a state law passed last year. The same is true in Texas, Alabama, Kansas and Hawaii, where in the past four years state governments have enacted bills forbidding cities and towns from requiring sprinklers in new homes. A dozen have forbidden statewide building code councils from including the requirement in their guidelines.