The repeal bill aims to achieve something pretty simple: when we leave the EU, all current EU law will become British law so that life goes on as normal after Brexit. Nothing more. It ought to be a rather boring, technical exercise in legal copying and pasting. Very dull. Nothing to see here.

So why all the fuss? Well it isn’t quite as simple as that, because lots of those EU laws will refer to EU institutions and rules that we will no longer be part of. So if we just copy and paste them over wholesale, they won’t work properly after we leave. They will need hundreds of small, detailed changes to iron out the wrinkles.

And imagine this. It’s March 2019 and we have 24 hours to go before our two-year negotiating period with the EU is up. Things are becoming increasingly fraught and, in time-honoured EU summit style, a lot of important issues aren’t agreed until the very last minute. Which means they all have to be written into UK law with incredible speed.

So the bill needs to do more than just “copy and paste”. It needs a bit of wriggle room so the new laws work properly, plus a bit more to cope with any changes that are agreed in the exit negotiations, too. And it’s got to work quickly, so everything’s ready by Brexit day as well.

As a result, the bill rather sensibly gives ministers that wriggle room they need, in the form of a two-year-long power to make changes through a standard process of cut-down lawmaking called secondary legislation, or statutory instruments (SIs). SIs are often used for small, detailed legal changes that don’t justify a full-scale act of parliament. They are a sensible way of keeping our laws up to date.

Some of the temporary ministerial powers are quite a bit bigger and broader than they need to be

MPs deal with hundreds of them every year, and no one ever notices or cares, because they are so trivial. They aren’t feudal relics; they have been deliberately created by (mostly pretty recent and modern) acts of parliament after extensive democratic debate.

And so it makes sense for parliament to use secondary legislation to process all the hundreds of detailed changes quickly so the statute books work properly on the day we leave the EU.

And that, you would have thought, should be that. Job done. Except that there is also an important, constitutional point to be made. There is a delicate balance to be struck between efficiently ensuring Britain’s laws keep working on the day after we leave the EU, and the fundamental, constitutional role of parliament.

The current draft of the repeal bill gives lots of power to ministers so we can deliver Brexit – which is essential – but it cuts parliament’s role right down. It’s not just me who is saying this. The House of Lords constitution committee has highlighted the sweeping nature of these delegated powers and said they raise “constitutional concerns of a fundamental nature, concerning as it does the appropriate balance of power between the legislature and executive”.

That’s because a tiny percentage of the legal changes during the UK’s withdrawal from the EU won’t be trivial or detailed at all; they will be really important and will need thorough debate in parliament. And some of those temporary ministerial powers are quite a bit bigger and broader than they need to be.

If Brexit is supposed to take back control of our laws, it’s pretty hard to argue that the small number of substantive changes should simply be waved through parliament without thorough debate. So I am suggesting two changes to keep the bill true to its original, impressively simple aims.

The first is to create a joint committee of both the Lords and the Commons to pick out the genuinely important statutory instruments from the hundreds of small ones, so they get thorough debate in parliament while the rest are processed efficiently. This will stop ministers from marking their own homework, and focus the democratic debate on what matters most, without giving anti-Brexiters an opportunity to gum up parliament with endless, pointless filibusters so that Brexit never happens.

The second is to limit the wriggle room that ministers are given, so they can only produce secondary legislation which is the bare minimum needed to make the new laws work properly, or to reflect whatever is agreed in the exit negotiations. Nothing more. So there’s no prospect of feudal decrees, because if ministers try to do anything more than what has already been agreed, they won’t be able to.

If we make these two changes, we will strike a delicate but vital constitutional balance. Brexit will happen on time, but Henry VIII will stay firmly in his grave. Let’s not disturb his slumbers; those days are gone.

• John Penrose is the Conservative MP for Weston-super-Mare