Samsung attorneys drew a bead on Apple's claims about the uniqueness of its iPhone design Monday, with stronger counterclaims about preceding designs or "prior art," citing three patent applications that preceded the iPhone.

Two Japanese patents and one Korean patent show a rectangular phone form with a large glass face and rounded corners. The glass face varies in size from one patent to the other, but all are much larger than older generations of phones. All three resemble the form of the iPhone, as well as the popular Samsung Galaxy line and its many variants.

The patent details were aired Monday in U.S. District Court in San Jose, Calif., before Judge Lucy Koh. The trial is in only its third day of testimony. It's expected to last three weeks.

Lead Samsung attorney Charles Verhoeven also highlighted some surprising differences between Samsung smartphones and the iPhone, differences that a key expert witness for Apple seemed unaware of. On the Samsung Galaxy S 4G, the rounded corners aren't rounded equally, as the iPhone's are, Verhoeven pointed out.

He asked key Apple witness Peter Bressler, an expert on industrial design, if he had noticed how much the top corners are a tighter curve than the bottom corners on the Galaxy. If part of a circle, the top corners would have a radius of 10 centimeters; the bottom, 13 centimeters, he said.

"I couldn't dispute your measurements," Bressler responded. "I haven't measured the corners" on the Galaxy, he testified.

[ Learn how Apple says Samsung infringed its patents. See Apple Execs: Samsung 'Ripped Off' iPhone. ]

Yet lead Apple designer Christopher Stringer, in testimony July 31, had insisted the rounded corners of the iPhone were one of its key differentiating elements. "Did you say equally rounded corners," Verhoeven had questioned him during his July 31 testimony, as if smitten by the idea for the first time. "Corners with exactly the same radii," Stringer had affirmed. Apple had settled on the design because it was "beautiful" due to its simplicity, balance, and symmetry, and part of the symmetry was equally rounded corners, he said.

Furthermore, Apple's design patents, which have Stringer's name on them, show only rectangular phone bodies with equally rounded corners. The point has been so prominent in the early days of the trial that it came as a something of a shock that no one had measured the rounded corners on Samsung's models, except, of course, Samsung.

Bressler, a graduate of the Rhode Island School of Design and founder of design firm Bressler Group, was introduced to the jury as having designed cellphones. Verhoeven later elicited the fact that he had not designed a smartphone and pointed out that none of his designs had been put into production. Only two or three had even been given shape as models. "Five or six" were made into mockups, Bressler corrected him.

Bressler had started out appearing to be the ideal witness to present an expert opinion on whether Samsung's designs had infringed Apple's. He is one of the 50 fellows chosen annually by the Industrial Designers Society of America and he is an adjunct professor teaching integrated industrial design in the University of Pennsylvania's engineering department. With his wavy gray hair and light gray beard and mustache, Bressler looked the part of a professorial and distinguished expert and he testified there was "substantial similarity" between the design of the iPhone and at least seven Samsung phones.

But that appearance faded somewhat as Verhoeven, known as Charlie V. in the courtroom, bore down on the witness. He had testified under friendly questioning by Apple attorney Rachael Krevans that the Samsung Galaxy S and other Samsung phones, such as the Infuse, Skyrocket, Vibrant, and Mesmerize, all infringed Apple's design, in his opinion. But Verhoeven asked detailed questions about the essential design elements of one phone after another to check how they infringed.

The questions challenged Bressler, then finally vexed him. "You're frustrating me in the level of detail you're asking about," he told Verhoeven.

"Mr. Stringer said details matter in industrial design," Verhoeven responded.

At another point, Bressler bristled: "You're asking me to compare peanut butter and turkey," he said.

"Which one is peanut butter and which one is the turkey?" Verhoeven asked quickly, drawing laughs from courtroom observers, including the 20 occupying the 21 back-row seats for the press.

But he came closer to drawing blood when one of his detail questions about a Samsung design elicited an inadvertent or unexpected response from Bressler. In evaluating one Samsung design, he said he didn't spend time inspecting and couldn't explain the four buttons at the bottom of the phone's face, a common element of Android design.

"You're not an expert in the (operational) functions of a smartphone? I thought I just heard you say that," Verhoeven said.

"I'm an expert on the function of design patterns," said Bressler.

Verhoeven: "Did you actually use any of those buttons?"

Bressler: "No, not as part of my understanding of the design of the phones."