How do states distribute the burdens of collective defense? This paper develops a network theory of burden sharing. We focus on bilateral defense cooperation agreements (DCAs), which promote cooperation in a variety of defense, military, and security issue areas. Using a computational model, we show that DCA partners’ defense spending depends on the network structure of their agreements. In bilateral terms, DCAs increase defense spending by committing states to defense activities and allowing partners to reciprocally punish free riding. However, as a state's local network of defense partnerships grows more densely connected, with many transitive “friend of a friend” relations, DCAs have the countervailing effect of reducing defense spending. The more deeply integrated states are in bilateral defense networks, the less they spend on defense. We distinguish two potential mechanisms behind this effect—one based on efficiency improvements, the other on free riding. An empirical analysis using multilevel inferential network models points more to efficiency than to free riding. Defense networks reduce defense spending, and they do so by allowing countries to produce security more efficiently.

The Transatlantic Trade and Investment Partnership (TTIP) has the potential to be a landmark treaty on many grounds. According to European and American officials, one of the main features that should differentiate the TTIP from other bilateral free trade agreements is, beyond its unprecedented scale, the ambition of its regulatory dimension. On both sides of the Atlantic there is a strong incentive to mitigate the impacts of “behind-the-border” obstacles that mostly stem from existing divergences between laws and regulations applied in Europe and in the United States. To do this, trade negotiators, together with policymakers and regulators, attempt, when possible and desirable, to facilitate the convergence of the policies that frame the European and the American markets. This paper analyzes how convergence may be reached with regards to the regulation of the digital economy, a relatively new area of interest in the field of trade law and policy studies, that seems to deserve a specific attention considering the growing importance it has taken at the domestic level and in the context of trade negotiations.

The United States and the European Union include several environmental clauses in their respective preferential trade agreements (PTAs). Building on an exhaustive and fine-grained dataset of PTAs’ environmental clauses, this article makes two contributions. First, it shows that the United States and the European Union have initially favored different approaches to environmental protection in their PTAs. The United States’ concerns over regulatory sovereignty and level playing field have led to a legalistic and adversarial approach, while the European Union's concerns for policy coherence have led to a more procedural and cooperative approach. Second, this article provides evidence that European and American trade negotiators have gradually converged on a shared set of environmental norms. Although the United States and the European Union initially pursued different objectives, they learned from each other and drew similar lessons. As a result, recent American agreements have become more European-like, and European agreements have become more Americanized. This article concludes that U.S. and E.U. approaches, far from being incompatible, can usefully be combined and reinforce each other.

The literature on policy convergence has identified numerous facets and causal drivers of convergence. Distinguishing four dimensions of convergence (object, benchmark, drivers and directed process) helps clarify why and in what form policy convergence may occur (or not). Thus, depending on, for example, the object of analysis (policy outcome or instruments used), the same empirical case may give rise to opposing assessments. Furthermore, both economic and political drivers are necessary to account for successful policy convergence: economic convergence partly explains why countries may face similar problems, and political mechanisms explain why they might choose similar policies to solve a given problem. This article illustrates the multifaceted character of convergence for the dynamic field of renewable energy policies in the European Union. The empirical results indicate temporary convergence in the case of policy support instrument choices and conditional convergence in terms of renewable shares. However, the results suggest divergence of public R&D subsidies targeting renewables.