All three current generation consoles have a form of parental lock-out controls. They're a good idea. A good idea that has, however, landed Nintendo and Microsoft in court.
Around Christmas time, 36 companies - including Best Buy, Dell, DirecTV, Motorola, Tivo and Wal-Mart - were sued by Guardian Media Technologies, who hold a patent for a digital classification control system. Nintendo and Microsoft are also among the accused, thanks to the parental control systems present in the Wii and Xbox 360.
But not Sony! No, Sony were smart enough to file a preventive against Guardian Media back in 2005, effectively covering their asses.
The suit has been languishing in limbo for nearly ten years now, but kicked itself up a notch late last year when it was found that, rather than being mere patent trolls, Guardian may actually have a case.
For those interested, there's a a far more comprehensive round-up at Ars Technica.
36 companies named in parental control infringement lawsuit [Ars Technica]