In an opinion issued this week, the U.S. Court of Appeals for the Seventh Circuit determined that U.S. fertilizer manufacturers can take several international companies to court over allegedly violating anti-trust laws by fixing the price of potash.  

The case, Minn-Chem Inc. et al v. Agrium Inc. et al, focuses on a group of seven companies that, as of 2008, produced over 70 percent of the world’s potash, which comes primarily from mines in Canada and areas of the former Soviet Union. The list includes companies based in Canada, Russia, Belarus and the United States.

The opinion states that these companies act as a cartel, which “initiated a sustained and successful effort to drive prices up beginning in mid 2003.” By 2008, potash prices had increased by at least 600 percent.

Potash, of course, is a mineral that is rich in potassium and a key ingredient in the manufacture of fertilizers.

Read the full ruling from the U.S. Court of Appeals.