Waaaay back in 2006, Agere Systems sued Sony. Said that the PSP (and some other Sony devices) infringed on their patent for a "wireless local area network apparatus". A key difference in this and other cases we see like this is that Agere aren't patent trolls: they're a proper tech company, and the judge found in Agere's favour, stating that Sony's infrigements were "wilful". Meaning Sony knew full well that they were infringing on someone else's patents, bu went ahead and infringed on them anyway. For their troubles, the Japanese mega-company must now pay Agere a cool $18.5 million. Sony fined $18.5 million in patent infringement case [PSPF]