If, like me, you’re just a casual follower of the Brexit news, then it’s likely that all you take in on a given day is a lot of roaring and shouting and talk of “no deal”. So what’s this latest row about Britain breaking the withdrawal agreement all about?

Here are some questions and answers:

What is the withdrawal agreement?

The agreement in question is the deal that was done last year between the United Kingdom and the European Union, which allowed the UK to leave the EU on January 1st this year.

What do they mean by “no deal” – I thought the UK was already out of the EU?

You are right. The UK left the EU on January 1st and is no longer a member. But the withdrawal agreement provided for a one-year “transition period” in which all the rules around trade between the EU and the UK would still apply, just as if the UK was still in the EU. So they’re out, but for one year, and one year only, they still get the benefits of membership.

So what is being negotiated now?

What they’re currently trying to work out is a trade agreement between the UK and the EU. What does that mean? Well basically, it’s about who can sell what, to who, and under what circumstances. For example, the EU is worried that Britain might lower its safety regulations on the production of food, allowing it to be produced more cheaply, and then selling it across the border. So a trade agreement will say things like “food exported to the EU must be produced to EU standards”.

The agreement will also deal with things like fisheries: The UK might insist that because it is outside the EU, there will be no more Spanish (or Irish) fishing boats in its waters. In return, the EU might want some other concession. And so a trade agreement often ends up being about more than just trade.

How is Britain “breaking the law”, exactly?

This all goes back to the withdrawal agreement, above, and the whole matter of the famous “backstop.”

The point of the backstop was to be an insurance policy for the Irish border if there was no trade agreement. Ordinarily, if there is no trade agreement between two countries, they must put up customs posts on the border, to check what is crossing, and to apply taxes and tariffs, and so on.

With the backstop, the border between Ireland and the UK, if there was no trade agreement, was effectively to be moved to the Irish sea. Instead of checks on products moving between Ireland and Northern Ireland, there would be checks on products moving between Northern Ireland and the UK.

At the time, this was largely thought to be moot by the British on the basis that there would be a trade agreement between the UK and the EU which would render the backstop irrelevant.

But now we are moving closer to the end of the year, with no trade deal immediately in sight. So under a “no deal” scenario on trade, the backstop would come into operation on January 1st.

And this is why there is a big row: Britain this week passed legislation that would empower the British Government to ignore the existence of the backstop altogether, and not check goods moving from Great Britain to Northern Ireland.

Why is Britain doing this? Isn’t it a complete breach of their agreement?

It is, indeed, a complete breach of their agreement. And it has been condemned by several prominent Brexiteers, as well as the usual suspects. But that doesn’t tell you why they are doing it, so this is what they say:

Boris Johnson, writing for the Telegraph this week, said this:

We decided in the Withdrawal Agreement to create a Joint Committee, in which we would thrash out the details of these new arrangements. It is here that things risk coming unstuck. We are now hearing that, unless we agree to the EU’s terms, the EU will use an extreme interpretation of the Northern Ireland protocol to impose a full-scale trade border down the Irish Sea.

We are being told that the EU will not only impose tariffs on goods moving from Great Britain to Northern Ireland, but that they might actually stop the transport of food products from GB to NI.

I have to say that we never seriously believed that the EU would be willing to use a treaty, negotiated in good faith, to blockade one part of the UK, to cut it off, or that they would actually threaten to destroy the economic and territorial integrity of the UK. This was for the very good reason that any such barrier, any such tariffs or division, would be completely contrary to the letter and the spirit of the Good Friday Agreement.

What he is saying, in essence, is that because there will be an EU border between Great Britain and Northern Ireland, the EU might effectively use it to impose a trade blockade between the two places in the event of no trade deal.

The EU denies this.

The Bill, Johnson says, does this:

But we cannot leave the theoretical power to carve up our country – to divide it – in the hands of an international organisation. We have to protect the UK from that disaster, and that is why we have devised a legal safety net – in the UK Internal Market Bill – to clarify the position and to sort out the inconsistencies.

This Bill protects jobs and growth across the UK by preventing barriers to trade between the nations and regions. It means that anything approved for sale in Scotland or Wales must be good for sale in England or Northern Ireland, and vice-versa.

So under the terms of the UK Government’s bill, the proposed checks in the Irish sea will be largely ignored.

What this means, in practical terms, is that the EU may have to resort to imposing a customs border on the island of Ireland, which they spent four years trying to avoid.

So what can be done about it?

There are, in essence, two ways out of this mess.

The first is that the UK Government bill is either defeated, or withdrawn. That seems unlikely, even though lots of Tory rebels have said they will vote against it. Boris Johnson has a huge majority in parliament, and is likely to get his way.

The second way is that a trade deal is agreed between the EU and the UK. In those circumstances, the entire row would become irrelevant.

What’s the deadline to get a trade deal done?

The effective deadline is the end of October. The current arrangements end on New Years Eve, and as things stand, the UK will have no trade agreement with the EU from January 1st. Businesses need about two months, minimum, to prepare for new trading terms, so if a deal is not done by late October, no deal is likely.