This work details 100 examples of how to design a user interface that guards against potentially harmful use errors. The examples cover myriad features concerning hardware, software, and documents with emphasis placed on medical devices. This analysis is timely considering the intense focus within multiple worldwide industries to increase the safety of products, tolls, machines and systems, including those used by professionals and laypersons. This intense focus arises from the revelation that preventable error is among the leading causes of death, in the same magnitude of heart disease...