One of the World Trade Organisation's most important but least known rules allows countries to introduce "remedies" against "dumping."
Note: This isn't my speciality so read replies from smarter people.
"Remedies" are targeted tariffs that address dumping. They are exceptions to the normal WTO rules in that they can be higher than bound (maximum) rates, and target only one country.
This is basically an economic study to determine if a product is being dumped, and if so, to what extent (how much more cheaply is it being sold abroad than it could be at home).
This would normally be a breach of the WTO rules, but was specifically allowed because of China's non-market economy status.
China's view was that as of that date, all future anti-dumping investigations against China had to be calculated using Chinese prices.
There are dozens of these remedy tariffs, and some are to the tune of 100% or more. A huge deal.
Hence this critically important case.
Would recommend watching this space. /end