Important ethical aspects apply to the process of obtaining consent in emergency critical care research: the incapacity of almost all patients for giving informed consent and the emergency and life-threatening nature of the conditions involved, resulting in short therapeutic time frames. We argue that deferred proxy consent is the preferable substitute for informed patient consent in emergency critical care research. However, researchers can face two problems when using this consent procedure. First, can proxies give a valid judgment for consent or refusal in the acute phase of the life-threatening illness of their relative, and second, what should researchers do with already obtained data when study procedures are finished (e.g., because the patient has died) before proxies can be informed and consent be sought? We propose approaching the relatives with information about the trial and asking them for consent only if it is ethically valid to do so. The first psychological distress may prohibit a complete understanding of the information, which is necessary for a true and valid informed proxy consent. In addition, we recommend using the study data if study procedures are finished before proxies can be informed and consent be sought, provided sufficient privacy measures have been applied.