A minister admitting that they are prepared to breach international law is highly unusual, a legal expert said.
But Dr Austen Morgan, a barrister in London and Belfast, said it may be merely posturing by the Government.
He said: "For anyone in the UK Government to expressly say they are going to breach international law or say they may do anything that by implication could be seen as a breach of international law is extremely unusual.
"I can only guess that the Johnson government is adopting a very particular pose here, of little UK against the Rest of the World for particular political relations.
"Whether there will be a breach is an extremely difficult question. International law cannot tell Parliament what it can or cannot legislate. Parliament is sovereign, Parliament can do what it wants under international rules.
"Ultimately I think this storm which is being created means very little because what I think the bill is going to do is talk about what is in the protocol in the international agreement."