Reason used a Swiss cheese model to represent accident causation and illustrate how an error can slip through despite overlapping system defenses and safeguards.Each slice of Swiss cheese represents a level of protection. However, safety gaps exist, and when gaps line up, errors occur. Unless a pattern of errors or evidence of reckless behavior occurs, a single event shouldn't warrant disciplinary action or termination. This concept underlies the tenets of a “just culture.”13 Nurses must be able to learn from their own mistakes and from the mistakes of others.