The article Informed Consent (Stanford Encyclopedia of Philosophy) lists some main arguments for informed consent. They are: "protection", "autonomy", "prevention of abusive conduct", "trust", "self-ownership", "non-domination", and "personal integrity". The article goes on to present counterarguments for it, and it seems to me that the justifications for informed consent are largely challenged, if not foundered. (A summary of this article is available in my website).
Anyway, the article seems to conclude that informed consent is not a natural right, but just a legal right. Here is the explanation:
One reason to take non-naturalistic approaches to the status of informed consent seriously is that not all natural rights are legally enforceable. Therefore, a moral informed consent right that is legally enforceable (as that right is usually taken to be in at least some institutional settings) may stand in need of additional moral justification, even if a natural right has been established. That additional, inescapable moral justification may then turn out to justify informed consent regulations even absent natural informed consent rights, say as trust-building measures. In particular, recall that many bioethicists ground informed consent in duties to treat rational, autonomous persons respectfully. Some such duties are clearly non-enforceable. For example, the moral duty not to lie to persons in breach of their autonomous decision-making is seldom legitimately enforceable. It is not the business of third parties to prevent me from disrespectfully and immorally lying to my friends. Thus, additional justification would be needed, beyond simple appeal to respect for autonomy, in order to establish an enforceable informed consent requirement. That inescapable additional moral justification may turn out, if successful, to justify informed consent regulations and the surrounding ethos in full. It may do so even if the project of grounding informed consent in autonomy, and all other attempts to justify natural informed consent rights, founder.
However, I don't understand this much, besides a vague understanding that there is an inescapable additional justification that makes informed consent a legal requirement. Can you help me explain (or re-explain) why that inescapable additional justification exists?
Note that this justification cannot be one of the above arguments, because they are challenged already.