<qa>  What is the potential for physicians to improve care?Importance: This implementation study phase III is an essential step in the process of developing a new clinical decision rule guideline for health care practitioners. Phase I successfully derived the Canadian C-Spine Rule and phase II confirmed the accuracy and safety of the rule and, hence, the potential for physicians to improve care. What remains unknown is the actual change in clinical behaviour that can be effected by implementation of the Canadian C-Spine Rule and whether implementation can be achieved with simple and inexpensive measures. We believe that the Canadian C-Spine Rule has the potential to significantly reduce health care costs and improve the efficiency of patient flow in busy Canadian EDs. 