Nowadays, the decline of the age of oil expecting in 2050 push many oil-producing countries to want to change their oil laws, to nationalize or expropriate foreign oil companies operating in their territories, to renegotiate their former petroleum contracts in order to better adapt them to the current circumstances and implement policies for strengthening the control of national and foreign petroleum activities. The rising of large (national or) foreign direct investments in search of new oilfield around the world reflects the panic of the decline of oil and its legal consequences. This situation will help us to analyze and understand legal issues that arise in the State contracts especially petroleum contracts signed between, on the one hand the host state of investment, subject of international law and owner of petroleum resources contained into its territory, and on the other hand, the foreign investors or a private foreign oil company, which is a non-state actor of international law. Keywords: State contract, Petroleum contracts, stabilization clause