The ethics of informed consent is relevant to self-experimentation. Informed consent is the principle that the volunteers in the experiment should fully understand the procedure that is going to take place, be aware of all the risks involved, and give their consent to taking part in the experiment beforehand. The principle of informed consent was first enacted in the U.S. Army's research into Yellow fever in Cuba in 1901. However, there was no general or official guidance at this time. That remained the case until the yellow fever program was referenced in the drafting of the Nuremberg Code. This was further developed in the Declaration of Helsinki in 1964 by the World Medical Association which has since become the foundation for ethics committees' guidelines.