San Francisco: Apple Inc and its allies on Monday will kick off a jury trial against chip supplier Qualcomm Inc in San Diego, alleging that Qualcomm engaged in illegal patent licensing practices and seeking up to $27 billion in damages. Qualcomm, for its part, alleges that Apple forced its longtime business partners to quit paying some royalties and is seeking up to $15 billion.

Filed by Apple in early 2017, the lawsuit in federal court revolves around the modem chips that connect devices like the iPhone or Apple Watch to wireless data networks. Qualcomm has spent the past two years mounting a pressure campaign of smaller legal skirmishes against Apple, seeking — and in some cases obtaining — iPhone sales bans for violating its patents.

The trial before Judge Gonzalo Curiel will play out on Qualcomm’s home turf of San Diego, where for decades the city’s National Football League team played in Qualcomm Stadium and nearly every business district hosts the mobile chip firm’s logo.

For Apple, the trial is about the freedom to determine its own technology path for blockbuster products by buying chips without having to pay what it calls a “tax” on its innovations in the form of patent licensing fees to Qualcomm that take a cut of the selling price of its devices.

For Qualcomm, the trial, along with similar allegations from US regulators in a January court hearing, will determine the fate of its unique blend of selling chips and licensing more than 130,000 patents.