NIST whose guidelines are admissible in court and a competent judge will take over expert testimony. (an expert witness who says something that contradicts these guidelines is guilty of perjury, though good luck persecuting that)
The rules of evidence govern what is admissible in court and I don’t recall any rule pertaining to NIST guidelines. I think what you might mean is that the guidelines are a learned treatise which, while it would be hearsay for me or you to quote as a fact witness, is nevertheless something an expert witness can refer to.
On one hand, I agree that just disagreeing with a guideline isn’t perjury. Especially in a case like this where lots of the industry still uses the old (bad, imo) plan.
On the other, an expert witness has specifically represented themselves to be an expert. Is there any level of incompetence that raises to the level of perjury in that case? IMO there ought to be.
That would be argued in cross-examination. A witness can be shown to be not a good witness. Perjury is very specific to knowingly lying while testifying under oath. We really don't want to expand it to areas of ignorance or disagreement; that way would stop people from testifying entirely.
