This week, the World Trade Organization ruled in favor of Canada in the latest round of a dispute that has been going on for nearly 40 years over tariffs imposed on softwood lumber exports coming into the United States.

The latest ruling stated that the U.S. tariffs imposed on Canada by President Trump's administration breached global trading rules because the administration had not proven its reasoning behind the tariffs—that the prices Canadian firms pay for softwood lumber harvested from government-owned lands are artificially low. 

The U.S. has taken the stance since the 1980s that the firms exporting lumber have the capacity to sell the wood for less than a competitive rate because they benefit from Canada's regulated forest industry. 

In 2017, the Trump administration imposed tariffs on the imports of up to 20%, but which have 14.25% in countervailing duties and anti-dumping duties of 6.58% on lumber, siding, and other softwood products. Softwood lumber is most commonly used in residential construction.