The Federal Tort Claims Act (aka, FTCA) allows certain negligence claims (including medical malpractice claims) against the federal government, but not against specific federal employees.  All that means is that your friend's claim would be filed against the agency that employs the negligent party or parties.  However, to sue under the FTCA, he must first file a notice of claim with the federal agency in question within two years of the accrual of his claim (usually when he became aware of or should have become aware of his potential claim).  The federal agency then has six months to resolve the issue.  If the agency denies any liability or takes no action, your friend can file a suit in the appropriate U.S. District Court.

Because the FTCA prohibits certain types of claims, and because of the timing issues discussed above, the notice requirement, and other technical issues relating to FTCA claims, your friend should contact an attorney who specializes in this type of legal action ASAP.  Initially, the attorney will help your friend establish who he should be suing and verify that the negligent party is in fact a federal employee.  The attorney will then be able to walk your friend through the process and ensure that no deadlines or technical requirements of the FTCA are overlooked.   Follow this link for my tips on finding a Massachusetts medical malpractice lawyer.  Good luck.