It's hard to keep track of when tariffs start; some are already here, and President Donald Trump has floated more.

The White House last month paused far-reaching “reciprocal tariffs” on dozens of countries, just hours after the measures took effect. Trump has also eased sector-specific tariffs targeting autos, and rolled back duties on some goods from Mexico and Canada.

Five small businesses urged a federal court to block Trump's tariffs but government lawyers contend presidents have long regulated trade.