This dissertation studies the impact of Medicaid expansion on the liability insurance industry. Within the three chapters, the first two chapters focus on the medical liability insurance industry, and the third chapter focuses on the auto insurance industry. Chapter 1, “Medicaid Expansion and Medical Liability Costs”, examines the impact of health insurance expansion on medical liability costs using the case of the Affordable Care Act’s (ACA) Medicaid expansion. Medicaid expansion has increased the demand for medical services, but in doing so it may also have increased physicians’ liability in medical practice. By studying malpractice costs to insurers, medical practitioners, and hospitals in the U.S. for the period 2010–2018, we find insurers operating in states with Medicaid expansion experienced significantly higher medical liability costs than those in non-expansion states. While insurers in expansion states did increase premiums, the increase was not enough to fully offset rising costs. Moreover, we find that tort reforms did not mitigate ACA-induced malpractice liability costs. We show this is because Medicaid expansion increased malpractice costs mainly by increasing claim frequency while tort reforms generally focus on reducing claim severity. We further find little evidence that hospitals paid higher malpractice insurance premiums, self-insurance, or incurred higher out-of-pocket medical liability losses after Medicaid expansion. Taken together, our results imply that it is medical practitioners and malpractice insurers who bear the rising medical liability costs. Chapter 2, “Medicaid Expansion and Medical Liability Insurance Prices” extends the first chapter to study the impact of Medicaid expansion on medical liability insurance prices for three specialties, internal medicine, general surgery, and obstetrics-gynecology (OB-GYN). As Medicaid expansion increased medical liability costs to insurers, they may react by increasing medical malpractice insurance prices. By studying counties in expansion states and non-expansion states and bordering counties with different Medicaid expansion status over the years from 2010-2018, we find that Medicaid expansion leads to significantly higher medical liability insurance prices two years after the expansion on average and the impact is strongest for internal medicine and general medicine but less so for OB-GYN. Our finding suggests that the expansion of health insurance could increase liability costs to medical practitioners. Auto insurance provides coverage of healthcare for injured drivers even for those without traditional health insurance coverage. The expansion of public health insurance provides low-income injured drivers with an additional source of coverage for medical bills. This may change drivers’ incentives for using auto insurance and the ultimate payments made by auto insurers. In Chapter 3, “Public Health Insurance Expansion and Auto Insurance: The Case of Medicaid Expansion”, we first use a simple theoretical model to illustrate how obtaining public health insurance mitigates the incentive of insured drivers to engage in claims buildup. We then empirically test how the Affordable Care Act (ACA)’s Medicaid expansion changed the medical costs covered by auto insurance. By studying private passenger auto insurers in expansion states and non-expansion states between 2010 and 2018, we find that Medicaid expansion led to significantly lower auto insurance losses and premiums. We further show that the results were driven by the decreasing losses and premiums for third-party liability insurers but not in the states with no-fault insurance. / Business Administration/Risk Management and Insurance

隨著近年醫療糾紛日益增加，民刑事訴訟程序冗長，醫病雙方長時間煎熬，醫病關係日益惡化，導致防禦性醫療盛行。本研究從醫療責任切入，討論醫療爭議及現行處理途徑與方式，現行醫療責任保險之發展，簡介外國醫療責任保險概況。探討我國實施強制醫療責任保險之可能性。 本研究試圖以多階層醫療風險處理模式，以達有效處理醫療糾紛事件之目的。該模式將建立強制醫療責任保險以提供基本補償及簡化賠償機制，推動醫療機構責任保險以行政手段加強民眾保障，限定賠償金額避免高風險急重症專科無人從事，提倡醫師專業責任保險分散風險，引進醫事審議仲裁機制縮短醫療糾紛審查及賠償程序。 期以多面向分層處理醫療糾紛及其賠償問題，建構安全的醫療制度，避免防衛性醫療的盛行及司法資源的浪費。 / With the growing number of medical malpractice cases and the lengthy process of both civil and criminal litigation procedures in recent years, the torture has been agonizing and worsening the relationship between physicians and patients. The very situation results in the prevalence of defensive medical treatment. This research deals with the problem from the viewpoint of medical liability, discusses the current methods of handling medical disputes and explores the development of current medical liability insurance. An overview of the situation in other countries is presented to investigate the possibility of implementing mandatory medical liability insurance in Taiwan. This research attempts to establish a multi-level mode to effectively resolve medical risks. This mode will contribute to a lot of functions including enforcing mandatory medical liability insurance, supporting a fundamental compensation and simplifying the process of damages claiming. Furthermore, the mode will also serve to promote the medical liability insurance of medical institutions and in turn enhance the protection for the common public with administrative measures. In addition, the mode intends to restrict the upper limit of damages in order to remedy the serious phenomenon that no doctors are willing to practice in the high-risk medical departments, which is expected to distribute the medical risk of all the doctors. It will also introduce a medical arbitration mechanism to shorten and accelerate the procedure of medical reviewing and damages claiming in handling medical malpractice cases. We hope, with the establishment of such a multi-level mode, a sound and wholesome medical system can be constructed and the overflowing defensive medical treatment and waste of judicial resources can be avoided.