The Haugheys had argued the 1921 Act was unconstitutional on the basis that a tribunal, vested with the rights and powers set out in the Act, was administering justice contrary to the Constitution.
They submitted the Act did not continue to be of full force and effect following the enactment of the 1937 Constitution because of the fact that the Act was inconsistent with the provisions of the Constitution.
The presumption of constitutionality is available only to Acts of the post-1937 Constitution, the Supreme Court said.
But, while there was no presumption of constitutionality in favour of pre-1922 Acts of Parliament or Acts passed prior to the coming into effect of the Constitution, the onus of establishing that a statute was inconsistent with the provisions of the Constitution rested with the person challenging the statute.
While the 1921 Act did not enjoy the presumption of constitutionality, the amending Acts of 1979-88, being post-1937 statutes, did, the court noted.
As the Haugheys challenged the continuing validity of the 1921 Act, and the amending Acts 1979-98, the onus rested on them to prove those Acts were unconstitutional.
The Haugheys had argued that the 1921 Act was unconstitutional on the basis that a tribunal, vested with the rights and powers set out in the Act, was administering justice contrary to the provisions of the Constitution which provided that justice should be administered "in courts established by law by judges appointed in the manner provided by this Constitution . . .".
The court said it was important to emphasise that while the tribunal is vested with powers under the 1921 and 1979 Acts, the tribunal itself has no power to enforce its orders to punish a person for failure to comply with those orders.
Compliance with such orders could only be enforced by the High Court.
It also noted that the question of whether a tribunal appointed by a minister on foot of an Oireachtas resolution and enjoying the powers vested in it by the 1921 Act was engaged in the administration of justice was considered in detail by the Supreme Court in the Goodman case.
The Chief Justice said the court entirely agreed with Mr Justice Hederman in that case in which the judge stated that the fact that certain powers are conferred on a tribunal of inquiry does not make such a body a court.
The court also agreed with the conclusion of Mr Justice McCarthy, who found there was no usurpation by the beef tribunal of the role of the judiciary in the administration of justice.
The court was satisfied that such statements were correct and applied to all inquiries and that the conduct of such an inquiry does not amount to the administration of justice.
"The critical factor is trial and adjudication, not inquiry," the Chief Justice said.
Mr Justice Hamilton added that the court was entitled to assume that a tribunal of inquiry will conduct its inquiry, as it is obliged to do, in accordance with the principles of justice and in particular with regard to fair procedures.