Apple and Nokia settled a patent lawsuit back in 2011, but now, they’re back at it again. This time, Apple is filing an antitrust lawsuit, not against Nokia but instead against third-party companies known as patent assertion entities, or PAEs, that are acting on its behalf. In retaliation for this lawsuit, Nokia is suing Apple directly.

In its lawsuit, Apple argues that Nokia already has agreements to license its patents for fair and reasonable terms, aka FRAND. But Nokia is transferring these patents to PAEs in order to aggressively pursue money. This, Apple says, shouldn’t be allowed because it’s “anticompetitive and abusive” to Apple and other technology companies. Nokia is separately suing because it believes Apple owes it money for patents used in Apple products.

The two companies last had a licensing spat in 2009, when Nokia sued Apple over claims that Apple infringed on some of its essential patents. These standard essential patents are used across the industry and as such, are supposed to be licensed on FRAND terms. This means companies can take advantage of these patents without paying outrageous licensing fees because they’re essential to most products.

and you thought this patent situation was settled

The companies eventually reached a settlement agreement in which Apple paid a one-time fee to Nokia and then was scheduled to pay regular royalties in the future.

Apple’s new lawsuit, which was filed in California, goes after PAEs that Nokia has partnered with to pursue additional patent money. Apple claims these companies, which include Acacia Research and Conversant Property Management, are “conspiring with Nokia in a scheme to diffuse and abuse [standard essential patents] and, as the PAEs and Nokia fully intended, monetize those false promises by extracting exorbitant non-FRAND royalties in way Nokia could not.”

Apple continues to say that these PAEs are able to pursue patent infringement cases because unlike Nokia, they don’t produce anything and instead built an entire business around fighting patent infringement. Apple implies the PAEs, and in particular, Acacia, has it out for the company, as evidenced by the number of patent lawsuits they’ve brought against it. PAEs have reportedly sued Apple at least 12 times based off former Nokia patents; by itself, Acacia has sued Apple more than 40 times based off patents from Nokia and other companies. Apple wants the court to declare this practice of routinely and aggressively suing based on other companies' patents illegal.

Meanwhile, Nokia filed a suit today directly against Apple in Europe and the US that claims the company is still infringing on Nokia patents. Nokia says that since settling that initial case, Apple has “declined subsequent offers made by Nokia to license other [parts] of its patented inventions, which are used by many Apple products.” So essentially, Nokia is arguing that Apple owes money because it takes advantage of more Nokia patents than it’s currently paying for. The lawsuit covers 32 patents, including display, user interface, software, and video-coding technology.

Nokia’s lawsuit is essentially retribution for Apple’s lawsuit, but Apple, while facing two opponents — Nokia and PAEs — is attempting to upend patent law. Apple’s case could ultimately be monumental in how future patent litigation is tried. That is, if it wins and doesn’t just settle things in a couple years.