President Donald Trump’s proposal to arm teachers in an effort to secure the nation’s schools has sparked national debate, but Texas has had armed teachers and staffers since 2008.

The Protection of Texas Children Law was passed in 2013 by Texas legislature, and allows public school districts and open enrollment charter schools to appoint designated School Marshal. The Marshals are intended to serve as a last line of defense in the scenario of a school shooting or an armed attacker enters a campus threatening the lives of the children.

School Marshal training includes a mental health evaluation, active shooter and emergency situation training, and firearms proficiency requirements—80 hours of classroom and simulation modules. The cost of training and certification is paid for by the School Marshal, unless funded by grant money.

The program’s anonymity makes it unclear how many School Marshals are currently employed, but state Rep. Jason Villalba, a Dallas Republican, told POLITICO he estimates 100 marshals are currently appointed throughout the state.

This legislation does not apply to private universities, and SMU has remained a weapons-free campus since 1994 under Texas “campus carry” law. Public universities and community colleges must allow campus carry in Texas. The law allows guns in buildings, classrooms, and dorms, but each campus makes its own rules on where weapons are permitted.