Navel-gazing politicians risk being left behind by businesses over Brexit, the president of Northern Ireland's Law Society warned.
Firms are moving much faster and operate globally, Ian Huddleston said. Some have already threatened to scale back UK operations.
Mr Huddleston said milk often travelled eight times across Northern Ireland's land border with the Republic during the manufacturing process and predicted that cross-border regulations which currently worked seamlessly would diverge after the UK exited the EU.
The senior lawyer who specialises in commercial law said: "The politicians have become very navel-gazing in their approach to this.
"Actually business is moving on much faster.
"They cannot wait for these answers to be found, so they will dictate their own timescales and their own agenda.
"Given the global flexibility that businesses have they will take their own conclusions."
The Government has said it is seeking frictionless arrangements on the Irish border post-Brexit and the EU has suggested it will be one of the first items to be addressed when negotiations begin later this year.
Businesses have raised concerns about red tape at the frontier, although Brexit Secretary David Davis has envisaged the movement of goods governed largely by technology.
Mr Huddleston addressed more than 400 lawyers visiting Belfast for the International Bar Association's Bar Leaders Conference.
He said the divergence in laws after Brexit would be even greater where power is devolved from Westminster.
"It is a good exercise for lawyers. It may not be as good for trade," he said.
A House of Commons library paper found 19,000 EU legislative acts, and another 7,900 UK statutory instruments employing EU law.
A total of 180 acts over recent years had EU influence.
The Brexit white paper estimated up to 1,000 statutory instruments will be required.
Eilidh Wiseman, president of the Law Society of Scotland, said: "This seems to me perhaps to be a rather conservative with a small c estimate.
"Maybe each statutory instrument will be several hundred pages long."