The High Court has been told that Liam Lawlor was a beneficial shareholder in a company that was not declared in the 1997 Dail Register of Interests.
Legal counsel for the tribunal has been presenting evidence today about a complex web of companies in which Deputy Lawlor was involved.
One such company, Clearview Ltd, was set up to control the laying of pipes in Lucan, Co Dublin.
The court heard that Mr Lawlor did not declare his 50% ownership of Clearview in the Register.
It was also told that certain documents relating to accounts in Liechtenstein and the Czech Republic had not been disclosed to the tribunal.
Mr Lawlor's legal team is expected to respond tomorrow.