Smartphone giant Apple and its South Korean counterpart Samsung are back in federal court. The companies are hashing out a patent infringement dispute that began in 2011, and the outcome of this case will determine how much in financial damages Samsung owes Apple.
In 2012, a jury found that “all three of Apple’s software patents on the iOS user interface were valid and infringed by a long list of Samsung devices, that Apple design patents were valid and infringed by several Samsung phones, and that Apple’s trade dress on the iPhone and iPhone 3G were diluted by several Samsung phones,” according to The Verge. The jury ruled that the infringement was willful, and said that Samsung must pay Apple $1.05 billion. However, after a 2013 retrial and other appeals, the financial damages were reduced, Bloomberg reported.
The current dispute is over roughly $400 million that Samsung was ordered to pay in damages over the design patent infringement. Lawyers for Samsung have argued that the damage amount should not be based on the profit of the entire device, but rather a portion, because only part of the phone was found to have infringed on Apple’s design patents.
A 2016 Supreme Court decision (8-0, with the decision written by Justice Sonia Sotomayor) said that the damages could be decided either way—the entire phone or a portion of it—and sent the case back to federal court for a jury to decide.
That is what brought the companies back to a San Jose, Calif. federal court. Judge Lucy Koh, who presided over a previous retrial, instituted a “Groundhog Day” rule, according to the BBC, meaning that no new evidence can be introduced, and the jury must not re-adjudicate the initial verdict that Samsung was found to have infringed on Apple’s patents.
The three specific design patents pertain to “rectangular shape, rounded corners and black glass of the iPhone’s front face,” according to Bloomberg. And for these three, the jury must now determine if the damages should be awarded on a percentage of profits from the whole device or a portion of the device—all based on a patent law written in 1887, according to USA Today.
There is a different formulation to determine the damages for the two utility patents, involving the bounce-back scrolling and pinch-to-zoom features, according to Bloomberg.
The jury will be selected on Monday, and the trial is expected to last five days, according to USA Today.
Samsung declined to comment on the case; Fortune contacted Apple for comment, and will update this article as necessary.