Apple and Nokia back with their patent fight, both the companies had settled a patent lawsuit back in 2011 and now they are back at it. Apple is filing an antitrust lawsuit, not against Nokia but instead against a third party companies known as patent assertion entities. In retaliation for this lawsuit Nokia is suing Apple directly.

According to The Verge, 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. On the other side Nokia is separately suing Apple because it believes Apple owes it money for patents used in Apple products.

According to Bloomberg, the Espoo, Finland-based company said Apple agreed to license patented inventions in 2011 but gas refused to extend those agreements that are now expiring. Nokia had filed a complaint with the German Regional Courts in Dusseldorf, Mannheim and Munich, and in federal court in Texas.

The dispute id rooted in Nokia's demise as the world's largest phone maker and seller company. Since selling its handsets business, the company has focused on networking. Nokia is now tapping its patent portfolio as a source of income, rather than as a cross-licensing tool to protect their own products.

However, 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 infringement.

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's lawsuit is essentially retribution for Apple's lawsuit, meanwhile Apple is facing two opponents at a time which are 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. Nokia Sues Apple to Escalate Mobile-Patent Licensing Battle