Ah thank you @CryptoFascistMadameCholet
I knew I'd seen it somewhere.
As @MissLucyEyelesbarrow says, a ban sends an important message even if it is difficult to police.
"About ten years ago, the Storting passed an exemption proposal which means that people who have children through surrogacy abroad cannot be punished. Toppe voted against the law change and still disagrees. "It is not a point for me to punish, but penal provisions are attitude-creating and support the seriousness of the legal provision. She says it is important to make it clear that there is a ban""
Of course the response from the pro-surrogacy lobby (from the article linked) is to open up the provision of surrogacy in Norway with regulations and that will mean people won't need to go abroad.
Just what our Law Commission here says. 