The Hollywood Reporter notes that the Delaware Supreme Court agreed with prior arbitration and rulings that Viacom owes $299 million with interest to the owners of the company at the time of Viacom's Harmonix acquisition in 2006 (which it would sell in 2010).
The legal dispute started getting heavy in late 2010, shortly after Viacom announced its intentions to sell the developer, when the former Harmonix owners sued the conglomerate for performance pay they were owed. Viacom attempted a counter-suit, but by the end of 2011 it was decided by an arbitrator that Viacom would need to pay.
Harmonix's law firm estimates the payout, including another dispute with the company, totals some $533 million. Viacom has not released a statement and Harmonix had no comment on the ruling.