AP
Rockstar is a company owned by Apple, Microsoft, Blackberry, Ericsson and Sony. Google actually tried to the patents itself, orginally offering $900 million then raising the price to as much as $4.4 billion. But it ultimately lost out to Rockstar.
The loss spurred Google to buy Motorola Mobility for $12.5 billion, in part to get its hands on patents.
These vendors would love it if judges would declare their competitors products in violation of patents and force them to stop selling their devices, even temporarily. If not that, they hope they can make their competitors pay them royalties.
It's all a legal game to make the other company's smartphone cost more.