Missouri Gov. Jay Nixon has signed legislation shielding security plans for public buildings and schools from open-records requests.
The measure permanently restores two exemptions to the Missouri Sunshine Law that expired in 2012.
One exemption covered operational guidelines and policies developed by law enforcement, public safety, first response or public health authorities for preventing and responding to terrorism incidents.
Another dealt with security systems and structural plans for property owned or leased by a government agency.
Nixon publicly called for the exemptions to be reinstated at a news conference last year with law enforcement officials. The measure passed the House and Senate this year without any opposition.