No. If it's not ECE, then it's not legal. And (If I recall) You can't buy and ECE helmet in the sates and have it be legal in Europe unless the dealer you buy it from is an ECE authorized importer.
I don't think ECE allows half shells, just open face or 3/4. I could be wrong though. ECE testing does have an open face requirement but I think the shell has to cover your ears, bringing you to the 3/4 helmets, well they are more like 5/8 helmets over there.
Here's another helmet I found I may buy when I find the ****ed money after I spent the dollars on the carbon one! I wear ear plugs and use my I Pod on occassion so the carbon helmet will work fine, but this one will work for you guys who want an I POD and a full face with stereo speakers in it! It only comes in silver, or so it says! But I really do like the Joe Rocket because it is so lighweight, I can't believe how light it is for a full face!
My helmet is an american import , looks identical to the uk spec helmet ( but I had to have matching colors of the busa ) , It has the same numbers on it inc the numbers on the visor as the uk helmet but does not have the uk sticker spec on the back , bought a sticker of ebay identical now
Dont think half helmets are legal at all , open face 3/4 is minimum requirment