It will be one of the main topics under discussion at a global conference of lawyers getting under way in Belfast this week.
More than 400 lawyers from around the world are taking part.
The Law Society and International Bar's Norville Connolly said Brexit was a huge issue for the profession.
"All UK lawyers at the moment can either establish or go into Europe to provide legal services," Mr Connolly said.
"Between England, Scotland, Wales and Northern Ireland there are a huge amount of lawyers who conduct business and create jobs and all that follows from that.
"If there's a hard Brexit, to use that expression, what will happen is that ability to travel abroad, to establish firms abroad, may well be lost.
"That's the fear that the lawyers who practise in Europe, or practise in some country other than their own country, that's their huge fear .
"So there's a lot riding on the hard Brexit v the soft Brexit."
A hard Brexit could have drastic consequences for the legal profession in Northern Ireland, according to the International Bar Association.