Simply put, the statement was that ECJ is supreme court of the EU and all states are subject to it's rulings and none can overrule it. The Guardian denied this.
So when the Guardian reports, over the Dripa case (Data Retention and Investigatory Powers Act, or snoopers charter), the following:
The result, though immediately significant, could prove academic once the UK has withdrawn from the EU and the ECJ no longer has jurisdiction over the UK
Now my memory may be faulty but the Guardian was arguing that less than 8% of UK legislation was subject to the ECJ. In fact this statement says something else entirely.
Other press were more honest in saying that the ECJ had levels of jurisdiction over 100% of UK legislation, although it had only directly legislated over about 8% of it (to date).
I like to collect these little things so we don't forget. Everyone is railing about how the Leave campaign lied and told mistruths.
Personally, I believe, that misquoting the amount of money we will, or will not, be getting back from not paying the EU is "playing the game". However I, personally, believe that lying about who has overall jurisdiction over the laws of the land in the UK; is Treason.
A somewhat different position. Which is why I remember them. Money is money. Control over the state and the powers of the state is a matter of Nation and National Security.