In March 1977, Switzerland ratified the Non Proliferation Treaty (NPT) signed in July 1968, thereby committing itself to use nuclear energy exclusively for peaceful purposes and to subject its nuclear materials (uranium, plutonium and thorium) to international safeguards. The NPT obliges all non-nuclear-weapon states to accept control measures by the IAEA. The corresponding Safeguards Agreement (CSA) was ratified in September 1978. In early 2005, Switzerland also ratified the Additional Protocol (AP) to the CSA. The AP contains additional obligations in the area of safeguards and closes specific gaps in the CSA.
After a complete revision of the Swiss nuclear energy legislation, the Safeguards Ordinance (SaO) came into force in February 2005 together with the Nuclear Energy Act (NEA) and the Nuclear Energy Ordinance (NEO). This was the first time that the Safeguards Agreement and the Additional Protocol were explicitly implemented in the Swiss law.