In this case study, the story unfolds in a courtroom where a family is seeking justice for their son who died from carbon monoxide poisoning. The family’s conversation and the lawyer’s questioning of the medical examiner demonstrate the role of hemoglobin and variables impacting the oxygen-hemoglobin dissociation curve. As the family seeks answers, students learn how environmental and physiological variables shift the oxygen-hemoglobin dissociation curve to the right or left. Students explore how these shifts change oxygen delivery to the systemic tissues and compare the affinity of fetal to maternal hemoglobin. The case concludes with a series of bioethical discussion questions. The case is primarily designed for a lower-level undergraduate physiology course. Students should receive instruction on hemoglobin and blood gas transportation prior to the case. It is also recommended that students have a basic understanding of the oxygen-hemoglobin binding curve as well as right- and left-shifts. Recommended pre-class preparation material is provided.