The march toward marriage equality: Reexamining the diffusion of same-sex marriage among states

The issue of same-sex marriage and lesbian, gay, bisexual, and transgender equality has received considerable attention from policy scholars. This is unsurprising given the issue is one of the defining social policy battles of the last decade. State governments at the forefront of this battle have responded by proposing a multitude of lesbian, gay, bisexual, and transgender-related policies. In this study, we comparatively assess the diffusion of two of these policies across US states: the legal recognition of same-sex marriages and state constitutional amendments defining marriage as exclusively between one man and one woman. While previous studies have examined the diffusion of same-sex marriage bans across states, none have offered a comparative examination of how both sides of this contentious issue have advanced their policy preferences alongside each other. Using event history analysis, we analyze a unique set of covariates to test two diffusion hypotheses: learning and imitation. We find that for both policies, policy learning is the primary mechanism occurring, suggesting that policymakers learn from one another for the same policy area, even if the policies have different motives or objectives. However, the effect of learning is more prominent for anti-gay policies, suggesting there are differences between policies.