What is the test for barring medical malpractice claims against an off-duty service member who sustained injuries in an incident to service?

In examining whether a service member's injuries were incurred "incident to service," the courts consider various factors, with no single factor being dispositive. The individual's status as a member of the military at the time of the incident giving rise to the claim is relevant. See, e.g., Persons v. United States, 925 F.2d 292, 296 (9th Cir.1991) (barring medical malpractice claim because off-duty service member "enjoyed the use of the naval hospital solely by virtue of his status as a serviceman") (internal quotations omitted); Appelhans v. United States, 877 F.2d 309, 311-12 (4th Cir.1989) (barring medical malpractice claim of service member on excess leave pending discharge).