Well they say they've patented some new tech that somehow does that. Who knows?
Here's the article:
PS4 DRM, price, release date, controller & specs news | Expert Reviews
Sony filed a patent late last year that could mean the PS4 won't play used or second hand games. The patent, US Patent Application 20130007892, describes "a game playing system including a use permission tag provided for use in a game disk for a user of a game, a disk drive, and a reproduction device for reproducing the game." Essentially, this means that a device similar to an RFID or or near-field communication (NFC) tag built into the game disc would tie it to a particular console or console user.
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