A European court will give its decision today in Apple and Ireland's appeal against a €13 billion tax ruling.
In 2016, the European Commission found Ireland breached state aid rules by giving Apple unfair tax benefits.
It ordered Ireland to recover the money plus interest - but both Ireland and Apple appealed the ruling.
Regardless of the outcome, a further appeal to Europe's highest court is likely.
If the 2016 decision is upheld by the EU's General Court today, Ireland is likely to appeal - and if it isn't upheld, then the EU is likely to appeal.
Solidarity People Before Profit TD Richard Boyd Barrett said any further appeal by Ireland would be outrageous.
He said: "I think it's even more unthinkable in the situation of COVID-19 - where we could desperately do with that money to help deal with the economic fallout - for the Government to even consider appealing the decision if the EU rules that €13bn plus interest is owed to this country in unpaid taxes.
"I think Apple's case for appealing the EU ruling would fall apart if the Irish Government pulled out of it - and that's what they should do.
"We shouldn't be assisting Apple in trying to avoid paying this money, because the country desperately needs it."
The appeal began after a two-year investigation by the European Commission concluded in 2016 that the Irish state allowed Apple to pay far less tax than other companies.
Explaining the decision in August 2016, the EU's then Competition Commissioner Margrethe Vestager said: "This selective treatment allowed Apple to pay an effective corporate tax rate of 1 per cent on its European profits in 2003 down to 0.005 per cent in 2014."
As a result of the ruling, Ireland was forced to collect the billions of euro from Apple.
However, the money is being held in an escrow account until the appeals process has concluded.