The Constitutional Court may uphold the law, throw out individual provisions and order the legislature to bring them in line with the Constitution, or throw out the entire law.

Erik Kerševan, a constitutional law expert who used to work as secretary of the court, told the STA the law was so short and internally inter-connected that annulment of individual provisions could render it immaterial.

Yet Kerševan also allows for the possibility that the judges annul the law but determine a legal framework for implementation of the tax in the interim period.

If the ruling is such that it prevents the government from collecting real estate tax, this could have serious implications for the budget.

As it stands, the tax is projected to bring in about EUR 320-340m this year, split in half between the national budget and municipal budgets; the state's share accounts for over 2% of total planned budget revenue for this year.

The court's decision will be based on six applications filed by the opposition as well as associations of municipalities, individual municipalities and the National Council.

A total of 13 articles have been challenged on grounds of violating the right to private property, equality before the law, and independence of local government.

The challenged articles deal with valuation of real estate, tax rates, the division of revenue between the state and local communities, and the right to recourse.

In February the court had stayed the implementation of a portion of the tax law and in effect prevented the issuing of binding tax assessments until it reaches a final verdict.