FORTUNE -- My favorite moment so far in the multi-billion dollar Apple v. Samsung patent infringement case came late Monday afternoon, the three-quarter point in what is shaping up as a four-week trial.
Samsung's legal team had just finished examining its second defense witness -- a Mistubishi engineer named Adam Bogue. Bogue testified that in 2003 he showed Apple (aapl) engineers a device called the Diamond Touch that allowed users to shrink and expand on-screen images by "grabbing" their virtual corners and pulling one way or the other. (See video below.)
For a juror inclined to accept Samsung's claim that there was nothing novel or original in Apple's pinch-and-zoom technology -- one of the patents Apple has accused Samsung of infringing -- the video Bogue showed may have been pretty persuasive.
Then Apple began its cross-examination. Howard Mintz, live-blogging for the San Jose Mercury News, describes what happened next:
Apple atty Mike Jacobs now crossing Bogue. Asks where the Diamond Touch unit he displayed back in the day is these days. Er, Bogue says, sold it to Quinn Emanuel. That would be the law firm representing Samsung. Quinn team scrambles to bring it in courtroom. It's some sort of tech monstrosity on a tripod now in middle of court.
As my tech brethren have quickly pointed out, this metallic creature now in front of the jury is not exactly the chill iPhone. Translation: Apple will say something like, "Are you kidding me?"
There, in something a bit larger than a nutshell, is the crux of what the jury must decide. For two weeks it's been shown Samsung products that appear to be deliberate copies of Apple's iPhone and iPad -- down to the pixels on the screens and the packages they're shipped in.
Now Samsung is trying to demonstrate that it was free to copy Apple's technology because Apple had copied every bit of it from someone else. (See Samsung's best defense: Everybody copies, even Apple.)
Will the jury find Mitsubishi's table-sized projection screen persuasive?
Hard to say. Especially since Apple hasn't finished its cross examination. On Tuesday it may point out that a company called Fingerworks was making multi-touch devices long before Mitsubishi built the Diamond Touch.
And Apple bought Fingerworks -- along with its patents -- two years before it introduced the iPhone.
The Diamond Touch video: