There's been a long-running theory that one reason medical costs are bloated is that doctors are scared of medical malpractice suits, so they order expensive and unnecessary tests to protect themselves from liability. But in three states over the past decade that enacted laws to put stricter limits on medical malpractice lawsuits, there hasn't been much of an impact in the volume or cost of emergency room care, a new Rand Corporation study shows. The finding suggests that doctors "are less motivated by legal risk than they themselves believe," casting doubt on the level of savings that could be achieved through medical malpractice reform, according to the study published in the New England Journal of Medicine on Wednesday.