I get really cross with this page, because it's the official government page and it's supposed to have a reading age of 9 to be easy to understand, but this is worded so rubbishly and sounds like you don't need to use a car seat for children over 3 AT ALL!! It's so stupidly, dangerously ambiguous. I think it's because in their site, it comes directly after a page called "When children need to use a car seat" but it's the first result that comes up (without the when they DO) when you google "when can children stop using a car seat?"
I've written to them about it but they just ignore me.
Many people will automatically insert a comma in between the two clauses, and understand as such:
*A child aged 3 or older can travel in a back seat without a child car seat, and without a seat belt if the vehicle doesn’t have one."
When what it actually means is:
If a vehicle has no seatbelts, a child aged 3 and older can travel in the rear without a child car seat or seatbelt.
What they really need is a massive great header saying "Exceptions to the car seat rule" and a bit of text first saying:
Normally, children must use a car seat up until age 12 or 135cm, whichever comes first. (Link to car seat rules page) Exceptions are made in the following situations:
- When the vehicle has no seatbelts, a child over 3 can travel in the rear, with no seatbelt or car seat.
- Children under 3 may not travel in a vehicle without seatbelts
- When it's a taxi, emergency, blah blah
This is a particular problem, because the booster/car seats from 3-12 rule came in in 2003, and previously it was only children up to age 3 needing car seats, with some people (not the majority) voluntarily using them to about 5-7 years, meaning that there is a bit of an awareness gap, mainly among adults born in the 80s.
If you were born before the 1980s, then you likely never used a booster seat, and possibly never used any car seat at all as a child, so you are highly likely to have looked up the rules independently when you had your own children to find out what was recommended these days.
But, if you were born before 1991, then you were already older than 12 at the time that the new rule came in and likely didn't pay attention to it. In fact, you can probably extend this to 1993 because of the height guideline meaning your parents might not have even mentioned it to you. You might have general awareness that younger children need car seats and probably remember other children using them, but may not be aware that children now need to use them up to age 12, or that the rule had even changed at all. If you ask your parents, they might remember age 3 or they might just say they stopped using it when you were nursery or school age. This is the current awareness gap because these adults are currently in their 40s and have children at the top end of the booster age range. They know that booster seats are required/the norm, but they assume that children age out of them at about 6/7 years old unless they specifically have reason to look up the law. (Which is why the poorly written gov page is a problem!)
If you were born between 1993-2002, then your parents were likely well aware of this change, you probably used a booster seat yourself right up to the age/height limit and might even remember being made to go back into a booster seat after you had stopped using one.
But if you were born a tiny bit later, say after 2002, then despite it being big news in 2003, if your parents were not paying attention to this news because they did not yet have children or they only had a newborn or a 1 year old for example, they might be vaguely aware of the fact that more people are using booster seats, but not be aware that the law has now changed. So there's another awareness gap here, and I think we'll see a dip in booster use for children aged 6-12 again in about 10-20 years' time, unless it's been so successfully established that it's culturally frowned upon to go without.
I doubt that's what your ex is doing, but I meant to comment on this earlier and now I'm hiding from a giant moth before going to sleep 
so you got the ramble anyway.