To my shock and dismay a small group of unelected peers are trying to shoehorn the Communications Data Bill (known as the Snooper’s Charter) into the Counter Terrorism and Security Bill as an amendment. This is a bad idea, and also an abuse of process. It would mean that neither the Lords nor the Commons would get a proper chance to discuss the details of what is a massive infringement of people’s privacy.

I served on the Joint Committee Nick insisted on, and we spent a year scrutinising it – and tearing it to shreds. Yes, we need the intelligence services to be able to do their job, but in the words we agreed unanimously “the draft Bill pays insufficient attention to the duty to respect the right to privacy, and goes much further than it need or should”.

That’s why we blocked the Theresa May’s plans to bring forward the Communications Data Bill. I am extremely proud we did. It is a fundamental liberal principle that there needs to be very good reason to infringe on someone’s privacy, not just the convenience of the security services.

And it’s not even clear how much any of the proposals will help! The benefits were described by our committee as ‘fanciful and misleading’. Advances in technology mean there is much more information about all of us than ever before. The haystack is getting bigger and bigger – and the bigger it gets, the more difficult it is to find the needles. We need better ways to identify the needles, not ways of collecting more hay.

Then there’s the cost. By the Home Office’s own count, it would add up to £1.8 billion. This is a huge amount of money, and I’m sure that we could find better ways of making ourselves safe with that money than monitoring everything we do online.

Crucially, something as massive as the Snoopers’ Charter shouldn’t be tagged onto the end of a Government Bill. We’ve secured a full review, and there is a process for thinking about this carefully by 2016, leading to a separate piece of legislation that can be considered properly in detail on its merits. Short circuiting this is cheating the system.

This amendment needs to be stopped. I know Lib Dem colleagues, with one disappointing exception, will be robust on this. Will Labour and the Tories? I do hope so, but given last time this subject came up in the Commons, Labour’s Yvette Cooper criticised Theresa May for not having brought the Communications Data Bill forward. It’s clear they both want to go further and be more authoritarian, but let’s hope the peers on both side see sense and stop it. For policy reasons and for process reasons, it must not pass.”

* Julian Huppert was the Liberal Democrat MP for Cambridge from 2010-15