The effectiveness of new assistive technologies must be carefully evaluated. The purpose of this study is to develop a protocol to evaluate the efficacy of new assistive devices. As a case study, we describe the evaluation of a simple, fail-safe wheelchair brake that reduces the risk of falls during patient transfers. The evaluation protocol includes a short-term evaluation of the efficacy and safety of the mechanical functions and a long-term evaluation of clinical use. The short-term evaluation confirmed the functionality and safety, and the long-term evaluation confirmed the reduction in the risk of falls.