I am not so sure if all the comments are based on thorough research. I am not at home so I cannot cite my sources, namely the relevant AS document. However I recall that the standards says it must comply with AS or relevant British Standard. The British Standard then says that their standard is interchangeable with the European Standard, a must since they have joined the EU.
I have imported a helmet from Europe which saved me over $ 200 including freight. I am waiting to get a ticket because I have my legal challenge mapped out!
Regarding the comment that the insurance won't pay. We all know that insurances are in the business of taking money and not paying out money. So they will find any excuse to not pay which means the onus of proof is on the other foot. I am happy to challenge the insurance company in court the same way as I will if the cops fine me. The law is clear, there must be a causal link between event and damage, ie. how did the helmet contribute to the loss suffered? If I can proof, and it won't be too hard, that the helmet I used is identical to the helmet certified AS it is clear that no causal link between helmet and damage exists. So what is the legal ground for them to refuse to pay?

Beware, even if you have an AS compliant helmet they will try to wriggle out of paying (if you have head injury) by claiming:
-you did not wear the correct size/type helmet
-your helmet had pre-existing damage ie. you previously dropped it/crashed with it etc. (therefore NEVER buy second hand helmets)
-you made illegal modifications, ie a sticker on it etc even though the manufacturer tells you to attached the supplied reflective stickers; what's the difference there?
-your helmet has been used past its use-by date, even though none is given when you buy it. However the law assumes a use-buy date through its it-for-use-intended provisions

whatever you do, they'll get you. always remember by importing a helmet you may save more than what the fine will be!

Yeah XB , had the same type deal , there is actually an article about these rulings and Cooney , owner of X-Rated Helmets on the back page of L2R issue No:292 which was pretty interesting !