High Court to hear Twiggy's MRRT case Fortescue Metals Group will appear before the High Court to challenge the government's mining tax. FORTESCUE Metals Group's challenge to the federal government's mining tax is set to go ahead before the full High Court. Fortescue is arguing that the Minerals Resource Rent Tax (MRRT) contravenes the constitutional right of the states to deal with their own assets and property in a manner that they see fit. In its first six months the MRRT delivered just $126 million to government coffers, against a full-year forecast of $2 billion. Fortescue will appear before the full High Court in Canberra on Wednesday morning. The firm's chairman Andrew 'Twiggy' Forrest has previously said the legal challenge is about conquering evil. In November he told ABC radio that all it took for evil to win was for good people to do nothing. "We've decided not to do nothing," he said.