Preliminary issues in a legal action brought by Sean Quinn's family against the former Anglo Irish Bank will be heard by the Commercial Court today.
The court will be concerned with whether the family can argue that loans they received were in breach of company law and other regulations.
Mr Quinn's wife, Patricia, and their five children are challenging claims by IBRC, formerly Anglo, that they owe €2.3bn.
They deny liability for the loans claiming they were advanced for the illegal objective of manipulating the stock market to prop up the bank's share price.
This is refuted by the bank and over the next three days IBRC hopes to narrow down the key issues in contention in a preliminary hearing before Mr Justice Peter Charlton.
The bank's lawyers say a full hearing could last months and cost millions.