Under a little-used federal law, hospitals that receive Medicare funding could be subject to penalties if emergency room personnel treat patients differently from other patients and their actions result in personal injury.

“This is a different way of looking at cases,” Leonard A. Simon, a Boston medical malpractice attorney, told a group of lawyers last week at the annual conference of the Massachusetts Academy of Trial Attorneys in Westborough. “This is a very powerful tool (for plaintiffs’ attorneys).”