About 40 percent of the medical malpractice cases filed in the United States are groundless, according to a Harvard study. Many of the lawsuits analysed in the study contained no evidence that a medical error was committed or that the patient suffered any injury, the researchers reported. The vast majority of those dubious cases were dismissed with no payout to the patient.

However, groundless lawsuits still accounted for 15 percent of the money paid out in settlements or verdicts. The study's lead researcher, David Studdert of the Harvard School of Public Health, said the findings challenge the view among tort reform supporters that the legal system is riddled with frivolous claims that lead to exorbitant payouts. "We found the system did reasonably well in sorting the good claims from the bad ones, but there were problems,'' he said.