The import duties imposed by the United States on Chinese goods two years ago violated international trade rules. This was decided by the WTO of the World Trade Organization.
The decision can still be challenged by the USA. Since the US has made the WTO virtually toothless with a number of measures, such a call actually means there will be no punishment. A U.S. complaint must be filed within 60 days.
The US imposed import duties on goods worth around $ 550 billion that China exported to the US in 2018. The move was part of the trade war that US President Donald Trump started with China. Trump believed that the trade balance between his country and China was too much in favor of the Asian country.
The US used a 1970s trade law for import duties. It was no longer in use when the Americans decided in the 1990s to first use WTO procedures to settle disputes before imposing import duties.