Thousands of licensees could be forced to employ or train up a second personal licence-holder (PLH) to ensure they are trading within the law.
Leading licensing solicitor Tom Henry of the Reece Jones Partnership claims the second wave of licensing guidance from the government, due in 2007 is likely to include a legal requirement for licensees to ensure there is another PLH on the premises while they are away.
Speaking at the Guild of Master Victuallers conference in Gravesend, Kent, Mr Henry said: "This may well become a requirement next year.
"You should start planning to have more than one PLH in your business now, if you haven't already."
Licensees have been advised since the start of the new Act to ensure they have two personal licence-holders in their business, but thousands are still thought to be reliant on one licence-holder.
Councils and police have shown continual confusion on the issue, with one licensee in Barnsley was forced to return early from her holiday in Spain after police shut her pub.
Mr Henry told delegates that the new guidance was also likely to include a restriction on the number of premises for which a designated PLH could be responsible.
He urged licensees to get involved in any consultation relating to the new licensing regime - and tell the legislators exactly how the Act was affecting pubs.
"We are heading back to the old days of the past, with more regulations, more red tape and considerably more expense on top of it," he said.
He also invited pubs to sign up to the Challenge 21-style policy on underage sales currently being promoted by the British Beer & Pub Association. "If you look for someone who is under- 21 rather than under-18 you will stay on the right side of the law," he said.