摘要:While federal institutional architectures furnish governments with authority to act autonomously in certain jurisdictions, they simultaneously require them to work together. In other words, federations variously combine self-rule and shared-rule. The scope and patterns of shared-rule in federations varies considerably across time and space. For example, the changing nature of the modern state in the twentieth century encouraged the emergence of a new era of cooperation in many federations. In contrast, the "new federalism" initiative in the United States, "open federalism" in Canada and "dis-entanglement" reforms in Germany and Switzerland represent efforts to restore self-rule and to trim back shared-rule arrangements. Mechanisms of shared-rule, however, not only vary depending on the historical context and the federal system, but can also take quite different forms. An extremely important, yet understudied form of shared-rule is the intergovernmental agreement (IGA), which lies at the heart of this ambitious comparative study by Jeffrey Parker.