@Doctor Syntax
You missed one key thing.
Their plan: Warrants issued against CLASS of crime. So a judge approves a warrant to get, for example [Vodafones log data], on reason of [big scary bogeyman of the day].
You could pretend that is a judicial check, with a warrant under your point 2. And that is what Cameron and May are pretending. It is not of course.
If the judge was given specific targets, e.g. 20 john does, believed to be communicating with RRR on DDD. Then a judge would issue a minimized warrant for data related to RRR on DDD. Vodafone in that case would minimize the data to fit within the judges order.
Vodafone would act as the enforcer of the judges order.
Instead they want bulk access. A surveillance order that hands them [All Vodafone data] or some bulk data set. Which they promise to filter for RRR+DDD, but its just a promise.
The judge in this case is just a tickbox. He could never have enough information to make a real judgement. Like the FISA court that approved access to data for particular purposes, only to find General Alexander had kept all the data and was freely using it in secret.
So what happens next?
Well UK has no meaningful checks and balances in its law, and no limits on who or where or what. So multinationals will be required to hand over all their data in all their foreign subsidiaries.
Which means every country in the world will follow. I think its already too later, even if we stop this law, the fact the British have grabbed all this data under the 1984 act (which targetted British telecoms companies, but didn't limit the data grabbed to Britain... think Vodafone Germany), will mean everyone will want to follow.
How happy are we if Microsoft has to hand all of its cloud data to China? Or British Phone logs to Russia? Just because these multinational companies have bases in those countries?
That is what happens next. If they pass THE EXACT OPPOSITE of this law, then we might be able to stop it. i.e. force companies to NOT DISCLOSE bulk data, NEVER IN SECRET, on serious penalties.
The next line of defense is encryption, compulsary encryption. We need our British data protected against this coming foreign data grab. Again Snoopers Charter kills encryption, it requires the company have a decrypted version of the data! ready for Russia and China to take too!
I don't thnk the realize just what damage they've done already, and this law is a catastrophy.