Unfortunately the likelihood of serious bodily injury caused by a firearm to politicians, state/federal employees, visitors, and the general public at these types of facilities is clearly foreseeable by a disgruntled/mentally unstable individual or by a domestic terrorist seeking a government-oriented target.  As a lawyer I feel much safer going into our courthouses, because I know that firearms are not permitted on the premises (with a few exceptions -- e.g., authorized court personnel).  Reasonable restrictions save lives, and these restrictions are narrowly tailored in their application.