If medical malpractice reform affects the supply of physicians, the effects will be concentrated in specialties facing high liability exposure. Many doctors are likely to be indifferent regarding reform, because their likelihood of being sued is low. This difference can be exploited to isolate the causal effect of medical malpractice reform on the supply of doctors in high-risk specialties, by using doctors in low-risk specialties as a contemporaneous within-state control group. Using this triple-differences design to control for unobserved effects that correlate with the passage of medical malpractice reform, we show that only caps on noneconomic damages have a statistically significant effect on the per capita number of doctors and that this effect is concentrated among only those specialties that face the highest litigation exposure.
Klick, Jonathan and Stratmann, Thomas, "Medical Malpractice Reform and Physicians in High-Risk Specialties" (2007). Faculty Scholarship at Penn Law. 1117.