The FDA's recent guidance on mobile medical apps creates a gray area in which the agency will not automatically require approval for all new mobile medical apps, but may exercise "enforcement discretion," depending on how the app functions, the risks it introduces to patients/consumers, and its intended use. Just as the FDA was issuing its mobile medical application guidance last fall, Block was helping a US-based healthcare system develop an app that would be used only by clinicians within that system. He became more intrigued when he inquired with the FDA as to whether or not his client would have to apply for a 510(k) clearance.