I'd have thought club rules are enforceable by law, if you have signed the flying order book and then do something that isn't alllowed then you have invalidated the club's insurance (have you not?) and therefore are breaking the law. Someone care to comment?
I guess that if you do something that's against the club rules, and the club has a loss from that, then the club can start a civil action against you. And rightly so, since what you did was a "breach of contract" (note: not directly "breaking the law"). But the CAA will stay out. However, if you break the law, it's the CAA who may come after you. In this thread, we're talking about what's *legally* allowed in your logbook.
And Bose already submitted that there are no insurance providers that he knows of (and he seems to have done his homework) that require proficiency above and beyond the law. So a club hiding behind "insurance requirements" to enforce a 28-day checkout is not really being honest to its members.
Note that I have no problems with clubs making and enforcing rules that do not directly stem from insurance requirements, as long as they don't announce them as "insurance requirements". But I do see a lot of organizations, aviation and non-aviation, use "insurance requirement" as a phrase to end all discussion about a certain rule, instead of being honest about things.