Power firms brought a legal challenge on Tuesday against a German government decision to shut down the country’s nuclear plants by 2022, a lawsuit that could allow them to claim 19 billion euros ($21 billion) in damages.

In a case that pits a struggling energy industry against the government, Germany’s Constitutional Court will examine the arguments of E.ON, RWE and Vattenfall, who want to be compensated for the closure.

The two-day hearing that opened on Tuesday comes five years after Japan’s Fukushima nuclear disaster, which triggered Chancellor Angela Merkel’s move to speed up the nuclear shutdown and reverse an earlier agreement that extended the lifespans of some plants.

The decision deprived the utilities of one of their main sources of profit and pitched them into crisis as the focus moved to renewables and electricity prices tumbled.

“I have great faith in Germany’s highest court,” Johannes Teyssen, chief executive of Germany’s largest utility E.ON, told reporters as he arrived for the hearing, adding the company had invested billions in nuclear technology.

“We paid our taxes, we paid our wages, we have done what every other company does with its investments.”

Environment Minister Barbara Hendricks said she was confident that the government would win the case.

While a decision is expected to take several months, the hearing could provide insight into the thinking on the eight-judge panel, either through its line of questioning or through comments that might hint at its eventual opinion.