California Gov. Gavin Newsom said Wednesday that his state will file a lawsuit challenging U.S. President Donald Trump’s authority to impose sweeping tariffs that have set off a global trade war.

The suit will argue that Trump’s use of the International Emergency Economic Powers Act to impose tariffs on Mexico, Canada and China, or a 10 per cent tariff on all imports, is unlawful. The act enables a president to freeze and block transactions in response to foreign threats.

California’s move follows rapidly changing tariff plans by the Trump administration. It is the first state to take legal action over the tariffs, which have been previously legally challenged in suits filed by law firms representing business owners and civil liberties organizations.