Defensive medicine—the practice of performing potentially unnecessary procedures or diagnostic tests to avoid the threat of malpractice liability—is thought to contribute to high health care costs in the United States. Because procedures and tests carry risks of complications, defensive medicine also may lead to adverse events. This secondary data analysis examined prospectively whether physicians who performed more cesarean deliveries (considered to be defensively motivated) were more or less likely to be subject to malpractice claims compared with those performing fewer cesarean deliveries. Researchers adjusted for available clinical characteristics and still found that obstetricians who performed more cesarean deliveries were less likely to have subsequent alleged malpractice incidents. This finding suggests that defensive medicine may be a rational physician response to the current malpractice environment, and underscores the patient safety rationale for malpractice reform. A previous WebM&M commentary discusses the causes and consequences of defensive medicine.