Known Unknowns: The realities of Brexit leave 'out' supports with an uncomfortable circle to square...
The Brexit vote is (finally) almost upon us and in less than 48 hours time we will know whether the UK electorate has voted to stay in the EU or to leave.
If it chooses the latter, the country faces significant challenges in terms of its future trading options with the EU. Gavin Barrett is Professor of European Constitutional and Economic Law at UCD - he joined Vincent Wall on Breakfast Business to outline what a 'leave' vote would mean for the UK.
"There are two things that we should remember if the UK public votes for Brexit," he began.
"The first is that no matter which option they choose, it will never put them in as good a position as that which they are in now. The reason for that is that they will be effectively locking themselves outside of the corridors of power for better or for worst at European level.
"The second point is that the price of access to the single European market of 500 million consumers is sovereignty and decision-making power. If you are in the EU that price is paid by sharing sovereignty and pooling it so you get a seat at the table.
Out campaigners have argued that Britain will be able to negotiate new terms to access the EU's Single Market - but Prof. Barrett says that this would be very difficult to achieve without major concessions - particularly when it comes to the free movement of people.
The most obvious route to go down would be to join the European Economic Area (EEA) with Iceland, Liechtenstein, and Norway.
However, these countries have had a fractious relationship with the EU. These states need to adhere to EU rules but do not have any negotiating power when its decisions are made. Mr Barret says that they are left waiting at the end of a metaphorical fax machine for rulings from Brussels.
The EU has less control over these states, this means that they can struggle to ensure that these states adhere to the rules of the Single Market.
These countries agree to the free movement of goods, people, services, and capital in order to access the market.
Prof. Barrett says that it is highly unlikely that the UK would be able to regain access to the single market without agreeing to the free movement of people.
Immigration and the free movement of people have been the most contentious issue during the duration of the Brexit debate. This leaves 'out' campaigners, who say that the UK can gain control over its borders without taking an economic hit with a circle to square.
"You can stop migration if you want - but you are very unlikely to get access to the single market," he concludes.
The matter is complicated because a 'leave' vote would be likely to result in the resignation of David Cameron (despite his claims that he will remain in office regardless of the outcome) - either leading to an election in the UK or a more Euro-skeptic politician replacing him and leading this difficult negotiating process.
After a swing towards an 'out' vote last week, polls have moved back towards the 'remain' side. A major rise in British and European stocks on Monday morning suggests that markets are expecting the UK to stay. The result of the referendum will be clear by the early hours of Friday morning.