Patient safety science applies systems thinking to healthcare delivery, recognizing that adverse events typically result from multiple system failures (Swiss Cheese Model, James Reason) rather than isolated individual errors. Each layer of defense (organizational culture, policies and procedures, supervision, training, technology, individual practice) contains latent conditions and active failures; an adverse event occurs when holes in multiple layers align, allowing a hazard to reach the patient. Just Culture framework distinguishes human error (unintentional slips, lapses, mistakes -- managed through system redesign and coaching), at-risk behavior (conscious deviation from safe practice where risk is not recognized or is believed justified -- managed through removing incentives for at-risk behavior and creating incentives for safe behavior), and reckless behavior (conscious disregard of substantial and unjustifiable risk -- managed through disciplinary action). High-reliability organizations (HROs) achieve consistently safe performance through five principles: preoccupation with failure, reluctance to simplify interpretations, sensitivity to operations, commitment to resilience, and deference to expertise. The nurse operates within a complex regulatory and ethical framework. The four bioethical principles guide clinical decision-making: autonomy (respecting the patient right to self-determination, including...