Ericsson has filed a lawsuit against Apple, accusing the tech giant of using bad faith tactics to lower royalty fees paid to Ericsson for the use of 5G technology.

This is the latest round in a long legal stoush that started in 2015 when the two companies started squabbling over royalty rates and patents for technology used in mobile phones. The pair signed a seven year deal, which Ericsson is now attempting to renew.

Now Ericsson has asked a federal judge to rule that the royalties it is asking for are “fair and reasonable”, in keeping with the law.

“Despite receiving substantial revenues from its sales of iPhones and other cellular devices, Apple has historically resisted licensing overtures by Ericsson, and other essential patent holders, as part of a global strategy to devalue standard essential patents and reduce Apple’s royalty payments,” Ericsson said in the complaint.