Although clinical decision support is an important safety tool, unintended consequences include frequent alerts with resultant alert fatigue and overrides. This observational study investigated whether override comments for clinical decision rules could be used to determine if a rule was broken. Investigators discovered that malfunctions were prevalent in clinical decision support. While the frequency of comments did not predict the presence of a rule malfunction, strongly negative comments were associated with erroneous decision support. The authors recommend routine monitoring of alert override comments to identify errors related to clinical decision support. A past WebM&M commentary recommended employing human factors engineering to make clinical decision support more effective.