In my experience mandatory helmet laws don't really work. You can force somebody to wear a helmet but you can't make them care.
Helmet use is mandatory here. Every day I see many, many people riding along with helmets that aren't done up, or are too small, too big, pushed way back so the front of the helmet sits on top of the head way back from the forehead etc.
I would rather see great training in road rules for cyclists than mandatory helmet laws, but I guess that costs money and is hard to implement, whereas wasting police time getting them to stop unlidded cyclists is easy.
Oh yeah, and I would also rather see laws on roadworthiness of bikes leaving shops (eg brakes must work) before helmet laws. I've never found a cheapo bike where the brakes can actually stop the bike in a hurry. (Actually this led to a comedy moment the other day when a kid we know who has a huffy bmx cheekily rode off on Mrs Geoff's Hayes9 equipped Caldera. When he tried to stop Huffy style he nearly went straight OTB :twisted
I've said it before and I'll say it again- I'd rather everybody was afforded every chance to avoid an accident than just slapping a helmet on them and hoping that will protect them when they do have an accident cos they've had no training and have no brakes.
...and yes, when in England, there are times (pootle around the lanes, a ride to the village etc) when I choose not to wear a helmet. I don't expect a lecture on my choice. It's my perception of risk and my head. :?