Not generally, no. Most of it is by convention coupled with the fact that no reputable journal will publish your work these days if you don't go through an IRB for certain types of work. There's also the funding angle, with most work being paid for by one of a few very large governmental bodies and each of those having stringent rules about what they do and don't permit.

Basically pursuing certain lines of research would make you unemployable thus (almost) nobody does it. Unless it looks likely to turn a profit in which case you can start a company and try your luck with VCs.

Presumably by intelligent, competent, analytical direct consideration.

The non-layman should get a pretty good idea at assessment (in this case, "where is nociception and is it there" etc.)

Allow me a relatively distant reference, for fun. Prosecution: "How do you know the patient was dead at the time?" // Doctor: "Because his brains were sitting on my table" // "And can you know for sure he was dead?" // "He could have been alive, brainless and practicing law maybe".

Which wants to mean, at least: surely there are subtle non easy questions, but still there exist thresholds of competence enabling better assessment. (And subtle doubts call for subtle defences, to be non-gratuitous.)