Clinical emergencies necessitate immediate action to avert the danger to the patient's life or health. Emergency patients might be in greatest need of novel therapies, and even presumed willing to assume some risk, but research into emergency conditions should be conducted under commonly accepted principles that fulfil the scientific, ethical, and legal criteria. Such criteria already exist in the US, but are still under development in Europe.This article introduces criteria upon which trials in emergency settings may be ethically and legally (...) justified in Europe. Based on both legal texts and professional guidelines, the author has established seven conditions for emergency research, of which informed consent and its substitutes, as well as the conditions of direct benefit requirement and necessity, are considered most problematic and therefore analysed more closely. Other conditions include absence of alternative methods, scientific validity, and approval by an ethics committee. (shrink)