If courts rule against the levies, international trade lawyers expect a messy period of red tape as refunds are processed and the administration scrambles to impose tariffs through other avenues.

Even though President Donald Trump often argues the US economy is booming under his watch, he warned Friday of a 1929-style crash if courts strike down his use of emergency powers to justify sweeping tariffs.

The Trump administration's tariffs are expected to raise $50 billion a month, with revenue going into the general fund.