More than three-fourths of US neurosurgeons practice some form of defensive medicine—performing additional tests and procedures out of fear of malpractice lawsuits. The rates and costs of defensive medicine by neurosurgeons are especially high in states with high-risk liability environments. "Although ordering extra laboratory tests, imaging studies, etc. was prevalent everywhere, it was even more so in high-risk states," according to the survey study by Dr. Timothy R. Smith of Northwestern University, Chicago, and colleagues.