That was never a legal (i.e. enforceable) requirement. It was also very poorly conceived and as applied, of questionable merit. It didn’t apply to renewals of licenses, only to upgrades and adding new endorsements, even if those endorsements had nothing to do with the Rule, e.g. Tankerman. If the applicable basis of the policy is everyone needs a refresher, it failed miserably as not everyone would ever take that refresher exam. A mariner who got an original license as OUTV or Master 100 and never upgraded could go an entire 20+ year career and never have to take that refresher, even if the rules themselves changed. Also, there was no objective evidence to support a conclusion that lack of knowledge of the Rules was a contributing factor in a disproportionate number of casualties as compared to other areas of professional competence. That a collision occurred doesn’t necessarily mean the mariner didn’t know what the rules contain (to use a possibly irrelevant analogy, an auto accident where driver X ran a red light doesn’t mean driver X didn’t know or forgot he was supposed to stop). There was also an issue of fees. Taking an exam at an REC requires payment of a fee. But since this exam was not legally mandated, no fees were collected creating an inexcusable accounting discrepancy, i.e. more exams were given than fees collected.
“In extremis” may not be in the rules, but it’s still in (case) law applying those rules. It’s still a valid term. It was first used in The Pennsylvania, 86 U.S. 125 (1873) and is still a valid doctrine. This case is the source of the Pennsylvania Rule that provides that if a vessel is in violation of a navigation statute at the time of a collision, it is presumed to be at fault. Note that a presumption can be rebutted and doesn’t by itself indicate liability. The use of the Pennsylvania Rule has been expanded to more than just Rules of the Road cases.