Post-Brexit the implementation of changes in UK rules on the recruitment of non-UK workers to take jobs in Northern Ireland is casting a shadow over business prospects for several important parts of the local economy.
There are proposals for the whole UK labour market that more restrictive eligibility rules should apply to all of the UK.
In Northern Ireland, restricting the arrival of non-UK workers may be a serious threat.
Quoting from reputable research, the NI Tourism Alliance said: "79% of tourism businesses cite the limited domestic labour market as the key reason for the continued need for EU workers."
For several key sectors of the local economy, each year they need to recruit several thousand employees from outside Northern Ireland.
On present plans, the UK Migration Advisory Committee will limit the number of potential employees coming into the UK using a policy framework that is designed to deter unskilled people and facilitate more people with skills and qualifications that will occupy jobs which have more attractive earnings.
Early proposals are that immigrants should be able to earn £30,000 a year: that would be well above the earnings of many current migrant workers.
There is no surprise that these proposals have already been widely criticised by employers in major industries.
Hospitality businesses, particularly hotels, food processors and farming (and fishing) interests have registered their opposition to changes that will make it difficult to recruit employees from countries where people are prepared to come to the UK because earnings in their home country are much lower than here.
The response to these changes affecting migrant employees should be either to persuade the UK authorities to amend the generality of the proposed immigration rules or to allow Northern Ireland (and possibly other regions) to treat immigration as a devolved topic.
If some degree of devolved decision-making is allowed then there will need to be a mechanism to try to regulate the movement of permitted NI migrants to transfer to jobs elsewhere in the UK.
People with long memories will recall that in the years before the UK and Ireland joined the EU, Northern Ireland did operate a Safeguarding of Employment Act which, in theory, restricted the employment of immigrant workers in Northern Ireland.
An additional dimension of the new controls on the recruitment of non-UK employees will be the influence of the UK-Ireland Common Travel Area.
The Common Travel Area offers UK and Ireland citizens freedom of movement, residence and employment across these islands.
The expectation is that this will be extended by the addition of defined rights for access to health, education and some aspects of social insurance.
One inconvenient restriction is likely to be a legal obstacle for non-Irish and non-UK citizens to cross the border from south to north to work in Northern Ireland.
Workers from other EU states will continue to have the rights of free movement of workers, as applied in the continuing EU, but would be subject to UK migration rules if they wish to move from RoI to NI.
The NI Tourism Alliance and Hospitality Ulster have already registered their serious concerns to the UK Migration Advisory Committee.
The Tourism Alliance reports that research has demonstrated that, simply in the aftermath of the 2016 referendum, 80% of businesses have already found recruitment more difficult.
An unsympathetic response from some UK government and official agencies has been that the vulnerable Northern Ireland industries should up their game and introduce efficiency and productivity improvements so that, instead of depending on the recruitment of low-paid employees, these vulnerable sectors would be able to compete whilst paying higher wages.
That aspiration to radically reshape working methods in farming, factories and hotels represents a long-term goal.
However, to survive in the years ahead any suggestion of early dramatic changes in working methods seems unrealistic and would be likely to damage the survival of some critical sectors.