This 5 minute video from the Wall Street Journal\* explains how tariffs usually work and what Trump has done differently to get all of these enacted so quickly.
[https://www.wsj.com/video/series/news-explainers/the-legal-logistics-behind-trump-lightning-fast-tariff-process/1BCBC478-DB0A-4693-8976-E1009877804B](https://www.wsj.com/video/series/news-explainers/the-legal-logistics-behind-trump-lightning-fast-tariff-process/1BCBC478-DB0A-4693-8976-E1009877804B)
tl;dw: Normally tariffs go through a lengthy planning and review process, but Trump got around this by calling the overall trade deficit picture a "national emergency". This is usually only done to sanction a particular country for some currently emerging reason. The dubious nature of this "emergency" may provide legal standing to contest the tariffs.
\* I know some people are going to say they don't like/trust the WSJ. If that's you, apply the "if even they are saying it, well then.." maneuver.