Which aspects of human-subjects research rules are actually laws rather than conventions?

Question

I'm aware that various laws exist regulating research on human subjects (Wikipedia summary here and in linked pages). However, I've had a tough time finding sources that clarify the boundary between legal restrictions and "guidelines". It's also not clear to me to what extent these laws apply to institutions (by governing what kinds of research they can fund/sanction) versus individuals (by governing what kinds of research activities can actually be performed).

So what I'm interested in is:

• Are there laws that make it illegal for an individual to violate or blur the boundaries of human subjects ethics guidelines, even though what is actually done would not be illegal if it did not constitute research? For instance, stopping someone on the street to ask them a question is not in itself illegal; does it become illegal if an individual does it to a lot of people and writes about it as research, without having the sorts of safeguards that an institution's IRB would require? I'm talking here about cases where the acts themselves would not otherwise be in question (e.g., the research doesn't cause physical harm), but only become potentially problematic because they are part of research.
• If research conducted at an institution violates ethical guidelines, is that considered an illegal act by the IRB or the individual, or both (or conceivably neither, if the violation wasn't covered by an actual law)? For instance, if a researcher submits a research proposal and has it approved, and then someone claims the proposal violates human subjects research guidelines, is it the wholly the researcher's fault for doing it, or does the IRB bear culpability for not properly vetting the proposal and alerting the researcher to the problems?
• Is there a specific mechanism for determining what counts as "research" subject to these rules in the first place? That is, is there an accepted legal framework for distinguishing informal information-gathering, not subject to the rules, (e.g., "Hey all my Facebook friends, everybody take this latest web quiz and post your results in comments!"), from bona fide research that is subject to the rules?
• Are there legal distinctions between different subject areas of research? A lot of the stuff I read on the issue mentions motivating cases that involved medical research, like the Tuskegee syphilis experiment. However, it's not clear to me if medical research actually has different legal restrictions than other kinds of research (e.g., sociological interviews or psychological questionnaires).

I'm mainly interested in the legal situation in the US, but would be interested to know about the law on this matter in other countries as well.

Also, I'm aware that in practice it often doesn't matter where the line is between what's actually illegal and what's just disallowed by university guidelines or scholarly consensus, because a researcher's reputation, career, and funding are vulnerable regardless of whether actual laws were broken. (In other words, even if you didn't break any laws, a journal may refuse to publish your paper if it smells a rat.) I'm asking this question on this site because I'm specficially interested in which restrictions on research activity are actually a matter of law, not just convention or institutional self-regulation.

Answer 1

According to the NIH, there are in fact a number of laws in the US regulating human research, as opposed to codes and conventions (although the majority does consist of the latter).

1. 1962 - Milestone: Kefauver-Harris amendments to the 1938 Food, Drug, and Cosmetic (FD&C) Act, [Public Law 87-781; 76 Stat. 788-89]

This amendment was important in establishing that human testing was necessary in drugs and therefore provided for the regulation of human testing, after the thalidomide scandal caused a number of preventable birth defects due to insufficient human testing.

The FDA describes the law as (emphasis mine):

... The Kefauver-Harris Drug Amendments also asked the Secretary to establish rules of investigation of new drugs, including a requirement for the informed consent of study subjects. The amendments also formalized good manufacturing practices, required that adverse events be reported, and transferred the regulation of prescription drug advertising from the Federal Trade Commission to the FDA.

2. 1974 - Milestone: National Research Act

The National Research Act legally justifies and grants the NIH the power to set up boards to regulate human medical research:

SEC. 102. (a) Congress finds and declares that (1) the success and continued viability of the Federal biomedical and behavioral research effort depends on the availability of excellent scientists and a network of institutions of excellence capable of producing superior research personnel ; (2) direct support of the training of scientists for careers in biomedical and behavioral research is an appropriate and necessary role for the Federal Government ; and (3) graduate research assistance programs should be the key elements in the training programs of the institutes of the National Institutes of Health and the Alcohol, Drug Abuse, and Mental Health Administration. (b) It is the purpose of this title to increase the capability of the institutes of the National Institutes of Health and the Alcohol, Drug Abuse, and Mental Health Administration to carry out their responsibility of maintaining a superior national program of research into the physical and mental diseases and impairments of man.