Their what ? Dress Trade Patents ?
Trade Dress is one thing.
Trademark another.
Design patents yet another.
Apple is claiming Samsung infringed on 3 types of their IP in this case. And yes, prior art and other models does come into play in showing whether Apple's patents are valid, patents are based on concepts that are novel (no prior art) and non-obvious (if a couple of entities came up with the same design at the same time, then it's pretty obvious).
Why do people refuse to inform themselves before posting and trying to "correct" others.

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And it doesn't apply in this case. This is not an exception. Why even bring it up ? It has no bearing on the discussion and it makes it seem like Apple already owns licenses to the Samsung/Motorola/Nokia 3G patents (well they do for Nokia now that they've settled that lawsuit).
That is what is lie, saying just buying the hardware gives you the license has people have claimed :
The truth is "it depends". And in this case it's "no, buying the hardware didn't grant Apple a license".
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That has no bearing on the design portions of Apple's claim. Apple's design patents make no mention of types of screens or lack/use of stylus/fingers.