US alder mill owners are challenging a special permission granted to Weyerhaeuser in 1999 which allows it to buy logs from Oregon state land.
The permission exempts the company from a rule which says timber exporting firms cannot buy wood from state forests.
Mill owners argue that Weyerhaeuser’s control of more than 70% of the US$400m Northwest alder market should prevent it from purchasing state logs.
Officials in Oregon will make a decision in October. A rescinding of the ban could see the case taken up in Washington state, where the company also has special permission to buy logs from 2.1 million acres of publicly-owned forest.
Earlier this year, Weyerhaeuser was told to pay out US$79m for violating antitrust laws by manipulating the alder log market. It is appealing against the ruling.
