One of the crucial patents in the court battle between Samsung and Apple is the slide-to-unlock control for the iPhone. Apple insists that it invented the technology.
However a video from a Microsoft researcher could spell curtains for that patent. University of Maryland researcher Catherine Plaisant has a 1991 video, entitled "Touchscreen Toggle Design" which shows off a number of ways to model a touchscreen toggle that users can control.
One of the toggles is an on-off slider that users can control by swiping their finger back and forth, which is exactly the method that Steve Jobs claimed he invented. However at the time, Jobs was the CEO of NeXT and had been disassociated from Apple for a good five years following his mid-80s topple at the hands of CEO John Sculley.
This means that Apple's claim that Samsung's phones violate its patent on the slide-to-unlock gesture might have to convince the court that Plaisant's invention was not prior art.
Florian Mueller, over at FOSS Patents, reckons Apple has argued in the past that Plaisant's video doesn't count because the company's patent governs sliding to unlock, and an on/off switch is different than that.
However saying that a sliding on/off switch is different than a slide to unlock switch just because one of them unlocks and the other does not is a fairly weak argument, but it is the only argument that Jobs' Mob can come up with.
Mueller pointed out that Apple's patent was invalid in Europe because the Swedish Neonode N1M used similar technology long before Jobs' Mob.
Apple still has a number of other patents that it claims Samsung infringes, for example another Apple patent at is about "rubber banding," which allows users to slightly scroll past the top of a document or view before it bounces back into place.
However having Apple losing the slide to unlock patent would weaken its case considerably. Jobs' Mob is hoping to get its rival taken off the shelf, or at least collect a huge court fee. But showing up with technology invented 10 years earlier by Microsoft does look pretty silly.