The Oregon Court of Appeals ruled April 28 that an exception to the state’s weight-mile system of taxing trucks is unfair to interstate truckers and unconstitutional, according to news stories.

The three-judge panel said allowing some in-state haulers of logs, wood chips, and gravel and sand to pay a flat fee instead of the weight-mile tax other truckers pay allows in-state truckers to pay less in taxes.

Therefore, the exception “puts interstate carriers at a disadvantage when compared with intrastate carriers,” the court said. The court added the exemption violated the U.S. Constitution’s Commerce Clause, which limits a state’s ability to regulate interstate commerce.