Invenergy is seeking PLN 1.2 billion ($325 million) in damages after agreements to buy wind power from four projects were terminated.
The US firm alleges Tauron "committed unlawful and unethical acts" in cancelling the agreements and indicated involvement of "former authorities of the Polish state treasury".
Tauron is majority-owned by the Polish state.
"We made a long-term investment in Poland with confidence that a legal framework existed to protect our investments from this type of behaviour. This case will test the assumptions of our original investment decision and signal to the market whether Poland is a country where investors can rely on the sanctity of contracts," said Invenergy CEO Michael Polsky.
Invenergy claims that after the 15-year power agreements were signed – with a Tauron subsidiary – the utility made "a series of actions to release itself and its... subsidiary of their obligations", which included a number of employees leaving the company.
In July 2014, Tauron began proceedings to liquidate the subsidiary, thereby annulling any power deal, which Invenergy challenged in court.
"Tauron never formally completed the liquidation but has done nothing to reverse the overall damage caused," the company said.
"Over several years, we made every attempt to work with Tauron and others in positions of authority to resolve this, and we asserted our rights in court cases, said Invenergy chief legal officer Michael Blazer.
"We were met with nothing but delays, obstructions and, ultimately, silence. Today's legal actions are an unavoidable result of Tauron's refusal to honour contractual obligations and the rule of law," Blazer added.
A statement from Tauron dated 3 July said the company had not received any lawsuit, but added the dispute was between Invenergy and its subsidiary, not Tauron itself.
