The objective of this dissertation is to evaluate whether two different types of policy interventions in the United States are associated with health service utilization and economic outcomes. Paper 1: The number of government lawsuits accusing pharmaceutical companies of off-label marketing has risen in recent years. We use Medicare and Medicaid claims data to evaluate how an off-label marketing lawsuit and its accompanying media coverage affected utilization and spending on gabapentin as well as other anticonvulsant medications. In this interrupted time series analysis of dual eligible patients with bipolar disorder, we found that the lawsuit and accompanying media coverage corresponded with a decrease in market share of gabapentin, a substitution of newer and expensive anticonvulsants, and a substantial increase in overall spending on anticonvulsants. Paper 2: Medicare Part D was a major expansion of Medicare benefits to cover pharmaceuticals. There were initial concerns about how the dually eligible population who previously had drug coverage through Medicaid would fare after transitioning to Part D plans. Using a nationally representative longitudinal panel survey of Medicare Beneficiaries that are dually eligible for Medicaid, we investigated whether differences in generosity of Medicaid drug benefits were associated with differential changes in drug utilization and out-of-pocket spending for duals after they transitioned to Part D. Our finding suggest that those who previously encountered a monthly drug cap prior to Part D implementation experienced a differentially higher increase in annual prescription drug fills compared with those who did not face a cap.