When Giants Clash: How US–EU Dispute Shaped GMO Treaty Ratification

Why States' Ratification Choices Matter

Christina J. Schneider and Johannes Urpelainen ask why some countries sign and ratify international treaties while others do not, even when domestic politics appear favorable. They focus on a neglected driver: conflict between powerful states. When major powers disagree about a treaty, their competition can shape whether third-party states adopt the agreement — a dynamic that matters for how international norms and rules spread.

Theory of Influence Between Powerful States

The authors propose a clear mechanism: when a powerful state defends the status quo, it has incentives to discourage other states from ratifying a treaty that would alter that status quo; conversely, challenger powers seek to entice third parties into ratification to build support for their preferred standards. This creates distributional pressure on middle and small states: their choices depend not only on domestic factors but on how dependent they are on, and how close they are to, the clashing great powers.

Case, Data, and Methods

Schneider and Urpelainen test the theory using the dispute between the United States and the European Union over regulation of trade in genetically modified organisms (GMOs). The EU promoted the Cartagena Protocol, which emphasizes a precautionary approach to biosafety, while the United States defended a “sound science” approach. The authors analyze third-party ratification behavior on the Cartagena Protocol with quantitative statistical tests that relate ratification decisions to states’ relations with and dependence on the United States and the EU.

Key Findings

• Third-party ratification behavior tracked the tug-of-war between the U.S. and the EU: states more dependent on one side were more likely to align with that side's stance.
• Supporters of the status quo exerted discouraging pressure on potential ratifiers, while challengers worked to entice them into the treaty.

What This Means for International Institutions

The results show that diffusion of treaties is not just a product of domestic politics or emulation; it is also shaped by distributional conflict among great powers. Understanding treaty ratification therefore requires attention to how powerful states leverage economic and political ties to influence others' choices, especially on technically complex or trade-sensitive issues such as GMO regulation.