Sign up to our free Brexit and beyond email for the latest headlines on what Brexit is meaning for the UK Sign up to our Brexit email for the latest insight
International law will force the return of checks at the Irish border if there is a no-deal Brexit , MPs have been told – despite Theresa May ’s claim she would never take bring them back.
Both London and Dublin would have “no choice” but to impose a hard border if the UK crashes out of the EU without an agreement, an expert in cross-border law said.
Dr Katy Hayward, from the University of Belfast, also warned of “dangerous goods” being smuggled into the UK if the prime minister attempted to defy the law and keep the border open.
Both the UK and Irish governments have said they will not introduce border checks, even as the risk of a no-deal Brexit rises with the talks deadlocked.
It follows warnings, including from police chiefs , that they would “play into the hands” of terrorists, by becoming an easy target for dissident paramilitaries.
But, Dr Hayward told the all-party Brexit committee: “If the UK is saying it is not enforcing a border at this point, there is a risk of smuggling of dangerous goods into the UK through its open borders.”
And, asked if governments could allow that situation to continue for “years”, she replied: “It’s not their choice to say whether they are going to enforce the border or not - they would be obliged to do so under international law.
“On the Republic of Ireland side, from the whole of the EU there would be an expectation that a customs border would be enforced.”
A historic moment: thousands march to demand Final Say on BrexitShow all 65 1 /65A historic moment: thousands march to demand Final Say on Brexit A historic moment: thousands march to demand Final Say on Brexit An estimated 700,000 people marched through London to demand a final say on the withdrawal agreement
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Red smoke from a canister hangs in the air as around 100,000 demonstrators march through London during a People's Vote anti-brexit demonstration savings banners and placards Anti-Brexit People's Vote March for the Future in London
Rex
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Mayor of London Sadiq Khan takes part in the People's Vote March for the Future in London, a march and rally in support of a second EU referendum.
PA
A historic moment: thousands march to demand Final Say on Brexit Final Say campaigners take part in the peoples vote march for the future in London 20/10/2018 Protesters wearing final Say shirts and holding placards
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit MP Chuka Umunna (left) and MP Vince Cable (right) as MP Anna Soubry (centre) addresses Anti-Brexit campaigners at a rally after the People's Vote March for the Future in London, a march and rally in support of a second EU referendum.
PA
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit A People’s Vote march attendee calls for a Final Say
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit Demonstrators with banners 'We're with EU' during the People's Vote March for the Future in London, Britain, 20 October 2018. Reports state that the 'March for the Future' is to be led by a column of young people and call for a People’s Vote on the Brexit deal. After marching through central London, there will be a rally on stage in Parliament Square, including speeches from Mayor of London Sadiq Khan.
EPA
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Protesters at London’s march for the future in October
The Independent
A historic moment: thousands march to demand Final Say on Brexit Editor of The Independent Christian Broughton speaks to demonstrators in Parliament Sqaure after they take part in a march calling for a People's Vote on the final Brexit deal, in central London on October 20, 2018. - Britons dreading life outside Europe gathered from all corners of the UK to London on Saturday to try to stop their country's looming breakup with the EU.
AFP/Getty
A historic moment: thousands march to demand Final Say on Brexit A poster at the March for the Future in October
The Independent
A historic moment: thousands march to demand Final Say on Brexit Anti-Brexit campaigners take part in the People's Vote March for the Future in London, a march and rally in support of a second EU referendum.
PA
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Final Say campaigners take part in the peoples vote march for the future in London 20/10/2018
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Anti-Brexit campaigners take part in the People's Vote March for the Future in London, a march and rally in support of a second EU referendum.
PA
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Demonstrators hold placards as they take part in a march calling for a People's Vote on the final Brexit deal, in central London on October 20, 2018. - Britons dreading life outside Europe gathered from all corners of the UK to London on Saturday to try to stop their country's looming breakup with the EU.
AFP/Getty
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit Final Say campaigners take part in the peoples vote march for the future in London 20/10/2018 campaigner wrapped in EU flag
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit
Angela Christofilou/The Independent
A historic moment: thousands march to demand Final Say on Brexit Final Say campaigners take part in the peoples vote march for the future in London 20/10/2018
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit Demonstrators pass Trafalgar Square as they take part in a march calling for a People's Vote on the final Brexit deal, in central London on October 20, 2018. - Britons dreading life outside Europe gathered from all corners of the UK to London on Saturday to try to stop their country's looming breakup with the EU.
AFP/Getty
A historic moment: thousands march to demand Final Say on Brexit Demonstrators wave Union and European flags and hold up placards as they pass Trafalgar Square, taking part in a march calling for a People's Vote on the final Brexit deal, in central London on October 20, 2018. - Britons dreading life outside Europe gathered from all corners of the UK to London on Saturday to try to stop their country's looming breakup with the EU.
AFP/Getty
A historic moment: thousands march to demand Final Say on Brexit Demonstrators hold placards as they take part in a march calling for a People's Vote on the final Brexit deal, in central London on October 20, 2018. - Britons dreading life outside Europe gathered from all corners of the UK to London on Saturday to try to stop their country's looming breakup with the EU.
AFP/Getty
A historic moment: thousands march to demand Final Say on Brexit A demonstrator holds a message during a march calling for a People's Vote on the final Brexit deal, in central London on October 20, 2018. - Britons dreading life outside Europe gathered from all corners of the UK to London on Saturday to try to stop their country's looming breakup with the EU.
AFP/Getty
A historic moment: thousands march to demand Final Say on Brexit Anti-Brexit campaigners take part in the People's Vote March for the Future in London, a march and rally in support of a second EU referendum.
PA
A historic moment: thousands march to demand Final Say on Brexit Demonstrators take part in the 'People's Vote March for the Future,' in central London, Britain, 20 October 2018. Reports state that the 'March for the Future' is to be led by a column of young people and call for a People’s Vote on the Brexit deal. After marching through central London, there will be a rally on stage in Parliament Square, including speeches from Mayor of London Sadiq Khan
EPA
A historic moment: thousands march to demand Final Say on Brexit A protester brandishes an Independent t-shirt during the Brexit March
Angela Christofilou
A historic moment: thousands march to demand Final Say on Brexit Anti-Brexit campaigners take part in the People's Vote March for the Future in London, a march and rally in support of a second EU referendum
PA
A historic moment: thousands march to demand Final Say on Brexit Tens of thousands of people take part in People's Vote March for the Future in central London. The march organised by the People's Vote campaign is led by young people calling for a People's Vote on the Brexit deal
Rex
A historic moment: thousands march to demand Final Say on Brexit Anti-Brexit campaigners take part in the People's Vote March for the Future in London, a march and rally in support of a second EU referendum
PA
Philip Hammond , the chancellor, has also privately suggested that World Trade Organisation (WTO) rules would force the UK to bring back checks without a deal.
And other EU countries are thought to have warned Dublin they would consider checks on trade from the Republic to the continent, if it failed to act.
Stephen Kelly, the chief executive of Manufacturing NI, said the notices simply told companies to contact the Irish government – telling the MPs the message was “have a word with the Irish, we'll come back to you”.
“The vast bulk of people are sitting with their heads in their hands looking for some clarity. The overwhelming reaction is one of worry, concern and waiting,” he said.
The stalemate in the Brexit talks is over the EU’s requirement for a “backstop” , to keep Northern Ireland aligned to EU customs and single market rules until a solution to avoid a hard Irish border can be found.
Ms May has called it “unacceptable” – and Tory MPs have branded it an “annexation” of UK territory – but Dr Hayward argued people in Northern Ireland preferred it to the damage from crashing out of the EU.
“A majority of business and civic leaders and political parties in Northern Ireland say a backstop is acceptable. If it’s between that and a no deal, a backstop is preferable.”
Aodhan Connolly, director of the Northern Ireland Retail Consortium, echoed that message, saying: “A backstop id not perfect, but is much, much preferable to the alternative of a no deal.
Warning beef prices would soar by 37 per cent, and cheese prices by 43 per cent, Mr Connelly added: “The Northern Ireland shopper does not have the ability to absorb these cost rises.”
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies