Retail bondholders protested outside the Council of State building in Athens on Friday as the court began hearing an appeal by private investors demanding their inclusion in last year’s debt write-down be annuled.

Some 600 protesters gathered in front of the court shouting slogans and holding black balloons that were later released in front of Parliament.

Bondholders have filed a lawsuit against the decisions of the Cabinet, the Bank of Greece governor and the alternate finance minister. They claim they lost up to 80 percent of their investment – including interest – and describe the fiscal benefit as “a drop in the ocean.” The defense says the private sector involvement (PSI) was in the best interest of the state.

About 11,000 people saw a big chunk of their investments go up in smoke in the debt restructuring program following Greece’s bailout deal with the European Union and the International Monetary Fund in March 2012.

The government had previously said that citizens holding Greek bonds worth up to 100,000 euros would not be affected by the debt swap. But then Greece used collective action clauses to increase participation in the program.

In comments made Friday, Dimitris Paxinos, former president of the Athens Bar Association, described the PSI as “unconstitutional” and urged judges to “rise to the occasion.”