Free Trade Agreements (FTAs) usually come with restrictions on the use of intermediate inputs in order for final goods to qualify for free trade. I focus on Rules of Origin (RoO), which limit expenses on nonmember country's intermediate inputs. In a three‐country FTA formation game, I introduce international trade in intermediate inputs and RoO restrictions. In the case of symmetric countries, I show that as countries become more involved in global supply chains, measured by their input shares in foreign final goods production, global free trade is less likely to be a stable equilibrium outcome. Free riding is the main problem preventing countries from liberalising trade. Countries are better off being nonmembers of FTAs between the other two countries relative to global free trade. Rules of Origin can solve this problem by limiting the benefits countries get from other countries' free trade agreements. In the case of asymmetric countries, an additional incentive exists for the smaller country not to join: such a country gives up more than it gains from joining an FTA for a sufficiently high degree of asymmetry in country sizes. I show that global free trade is a stable Nash equilibrium under a larger region of asymmetric country parameter space in the case of RoO than without it. Therefore, it is shown that RoO is essential in order to attain global free trade.