I've just signed up successfully, but to do so of course I lied - I have no intention of subjecting myself to any laws of the US (at least unless I happen to visit there). Anyway, asking people whether they agree to be subject to laws is fundamentally stupid - if a law applies to you, it applies whether you agree or not.
It might make sense to say that since this forum is hosted in the US (and presumably at least one responsible person is subject to US jurisdiction), any relevant US laws apply to the way the board is conducted, but that's about it.
