SAN JOSE, CALIFORNIA—The gargantuan Apple v. Samsung trial isn't just about Apple's claims that Samsung copied its flagship products. After it was sued, Samsung used its own patents to go after Apple, and the San Jose jury will soon issue a verdict on both sides' claims.

Today Samsung unleashed its counterattack, putting an expert on the stand that accused Apple of infringing three patents with incredibly wide-ranging claims to basic smartphone functions.

The Korean electronics giant claims to have one patent that covers multi-tasking while playing music (No. 7,698,711); another that covers "bookmarking" the last-viewed photo in a smartphone for easy retrieval (7,456,893); and even one that the company says covers sending an e-mail with a photo attached (7,577,460).

A Samsung expert witness, Harvard Professor Woodward Yang, walked the jury through the claims of the patents he said were infringed by Apple products like the iPhone 3GS, iPhone 4, iPad 2, and the 4th-generation iPod touch. Yang, who was paid $550 an hour for his work on the case, described each claim in simple terms, and narrated along as videos on the slide showed a demonstration of how each patent was used by Apple products.

"You're looking at a picture, and if you go to do another function—you've lost your place," said Yang, describing the '893 patent. "The idea was, let's have a bookmark."

A video played for the jury, showing a screen split four ways: iPhones and an iPad all viewed a vacation photo, then took a photo of an orange. After going back to the photo gallery, the vacation photo came up immediately.

"That's very convenient," explained Yang. "Without this invention, you'd now be looking at the picture of the orange."

(The iPhone 3G wasn't accused on that particular patent, since the feature was added later.)

Later, Yang walked through Samsung's music-multitasking patent. A video showed a user picking a song, then going back to e-mail and other applications.

"I could be reviewing my mail while I'm listening to Bruce Springsteen," said Yang.

The features on display in the three patents were only added to the iPhone after they were patented by Samsung, the company's lawyers alleged.

On cross-exam, Apple's lawyer, Bill Lee, didn't challenge the Samsung patents directly. Instead, he suggested that Apple's devices don't meet terminology found in the patents, like a "silent mode." He also noted that Yang has made about $200,000 working on this lawsuit, and a similar amount in a lawsuit involving Nokia.

The Samsung counter-attack isn't over; in addition to the user-interface patents that Yang testified on, the Korean company has patents it says cover the 3G wireless standard that Apple is infringing.

Making a case for damages on specific user-interface features can be wildly speculative. An Apple expert in this case believes that the patents involved in this case add $90 per smartphone. In a smartphone trial scheduled to start earlier this year, Apple v. Motorola, the judge overseeing the case deemed the damages arguments so weak he canceled the trial altogether.

The way the jury will see a strategy like Samsung's is hard to predict. Patent counter-attacks can be seen as vindictive, or they can convince a jury that both sides' claims have a kind of parity, with each having important intellectual property.

Testimony continued in the afternoon, with a Samsung designer named Jeeyeun Wang taking the stand.