Virginia Waffen (plaintiff) was a patient of the National Institutes of Health (NIH). There, Waffen underwent an x-ray, and a radiologist’s report recommended a follow-up examination for an apparent mass lesion. The radiologist’s report was misplaced by NIH personnel and not included in Waffen’s file. Seven months later, an x-ray from another hospital showed that Waffen had terminal cancer. Waffen brought suit against the United States Department of Health and Human Services (DHS) (defendant) under the Federal Tort Claims Act for medical malpractice by NIH. The district court found that Waffen failed to prove that the seven-month delay in treatment was the proximate cause of her terminal condition. The claim was dismissed. Waffen appealed. The United States Court of Appeals granted certiorari.