- The right to refuse medical intervention is well established, but it remains unclear how best to respect and exercise this right in life support. Contemporary ethical guidelines for critical care give ambiguous advice, largely because they focus on the moral equivalence of withdrawing and withholding care without confronting the very real differences regarding who is aware and informed of intervention options and how patient values are communicated and enacted. In withholding care, doctors typically withhold information about interventions judged too futile to offer. They thus retain greater decision-making burden (and power) and face weaker obligations to secure consent from patients or proxies. In withdrawing care, there is a clearer imperative for the doctor to include patients (or proxies) in decisions, share information and secure consent, even when continued life support is deemed futile. How decisions to withhold and withdraw life support differ ethically in their implications for positive versus negative interpretations of patient autonomy, imperatives for consent, definitions of futility and the subjective evaluation of (and submission to) benefits and burdens of life support in critical care settings are explored. Professional reflection is required to respond to trends favouring a more positive interpretation of patient autonomy in the context of life support decisions in critical care. Both the bioethics and critical care communities should investigate the possibilities and limits of growing pressure for doctors to disclose their reasoning or seek patient consent when decisions to withhold life support are made.