Many thanks to my good friend Jonathan Gershater for sending me the link to another excellent post about Identity and Healthcare.  I particularly like his illustration of using Federated Identity to facilitate trusted exchange of medical records between different medical service providers. 

A user of any (Healthcare) ServiceProvider, who has been issued a digital identity by the trusted IdentityProvider, may seamlessly interact with the healthcare providers (SPs). The user will present the digital identity issued by the IdP, the SP will verify the Identity, and the user will be granted access to the Service Provider’s application. However, based on the user’s attributes and role, the functionality available to the user will vary.  A physician may alter a medical record but only within their specialty ( a dermatologist cannot alter a prescription for spectacles). A pharmacist may view but not alter the prescription for insulin in a healthrecord.  A patient may only view but not alter their medical record.