The 14-day quarantine scheme is at a considerable risk of becoming a failure before it even gets started here, the Police Federation of Northern Ireland has warned.
The organisation, which represents rank-and-file officers, criticised the controversial measure after authorities admitted they are not yet prepared to enforce it.
The new legislation will require anyone who enters Northern Ireland from outside the UK and Republic, both visitors and holidaymakers returning home, to self-isolate for a fortnight.
However, travellers to the UK can avoid self-isolating by taking advantage of a loophole dubbed the 'Dublin dodge', which involves travelling to the Irish capital first and then straight on to the UK.
Overseas visitors arriving in Dublin but heading across the border do not have to reveal where they are staying here, meaning they are unlikely to face checks that they are abiding by the rules.
Chief Constable Simon Byrne admitted on Thursday the PSNI is still seeking clarification over how it can police the loophole - three days before the new policy comes into effect.
The PSNI's admission comes as the Health Minister insisted there had been widespread engagement on the island of Ireland for the policy arrangements to be in place by the date the rule will come into effect on June 8.
However, while those in Britain who flout the requirement face a fine of £1,000, the penalty figure has yet to be set here.
Despite the assurances from Mr Swann, Police Federation chairman Mark Lindsay insisted the policy is futile when it comes to the policing of the quarantine.
"These new quarantine rules present real challenges for policing given the ambiguous nature of the proposals to date," he explained.
"There is no realistic prospect of imposing quarantine checks on travellers who arrive via the Republic of Ireland."
He continued: "Without shared documentation and cooperation with the authorities in the Republic, the scheme will prove to be unworkable, unenforceable and ineffective.
"More complex powers could be needed to ensure compliance with the regulations and random checks could be a significant drain on available police resources.
"The success of such a scheme will rely on the common sense of the general public and not through a myriad of police powers to ensure the health of them and their families are protected.
"A lot more thought is required if this scheme isn't to be labelled a failure before it's even rolled out."
The criticism comes as a government scientific adviser cast doubt yesterday over the government's claim the scheme was "backed by science".
Professor Robert Dingwall, a member of a sub-group of Sage (Scientific Advisory Group for Emergencies), said there was no evidence of new clusters of Covid-19 infection involving people who have been travelling abroad.
"I think we would really need to get the level in this country significantly further down before quarantine started to become a useful measure," he said.
"Even then, we would have to see something that is targeted on countries with a significantly higher level of community transmission than ourselves - and there aren't too many of those around, I'm afraid."
Meanwhile, the Northern Ireland Secretary of State, Brandon Lewis, admitted the policy has discrepancies, such as the fact that a family from Spain could visit the Lake District for a holiday, while a family from London cannot.
But he told BBC Breakfast the policy is necessary, claiming it will be enforced strictly.
Ryanair boss Michael O'Leary said the scheme will "do untold damage to British tourism", echoing comments from Belfast International Airport managing director Graham Keddie who warned the requirement will have "very severe economic and social consequences" in Northern Ireland.
Mr Byrne admitted at Thursday's Policing Board meeting that the PSNI is still grappling with the policy.
"Basically, suffice to say there isn't clarity yet. So we still await guidance from the government and the Executive," he said.
But Mr Swann has insisted progress has been made in implementing the scheme, although he conceded at Thursday's daily Covid-19 briefing that compliance is ultimately down to the individual.
"We are working very closely with the Irish authorities at this minute in time to make sure that anyone who lands either in Northern Ireland or southern Ireland does take the responsibilities seriously," he explained.
"We have an electronic form that will be filled out at the point of arrival, no matter where you land or arrive on this island. So there is the sharing of information.
"Both authorities are working very closely in regards to leaflets and posters that will be available and mandatory on display where you arrive to point out that the regulations and the restrictions are there for your point of destination, and where you live - not where you arrive."