“On what grounds is it ever justified to regard consent as having its purported normative consequences? In special circumstances there may be a variety of occasional reasons that make the consent valid. Most common, perhaps, are those cases where the person to whose rights the agent consented was misled, through the agent's fault, into believing that the consent was valid and acted reasonably on this belief to his detriment. The agent might, for example, be at fault if in the circumstances the consent could be taken as sufficient evidence that the agent has power to consent (i.e., that there were reasons for holding the consent valid) and the agent should have realized this. In such cases the agent's liability is to make good the detriment thus caused to the person to whose rights he consented. Occasionally this requires recognizing that the consent and the circumstances surrounding it create the rights it purported to create.”