Speaking to GameTrailers, Sony America CEO Jack Tretton revealed that third-party publishers for games on the PlayStation 4 can dictate their own DRM terms for the console, although Sony first-party titles will not implement DRM. He said:
Well, I mean, we create the platform, we've certainly stated that our first-party games are not going to be doing that, but we welcome publishers and their business models to our platform. There's gonna be free-to-play, there's gonna be every potential business model on there, and again, that's up to their relationship with the consumer, what do they think is going to put them in the best fit. We're not going to dictate that, we're gonna give them a platform to publish on. The DRM decision is going to have to be answered by the third parties, it's not something we're going to control, or dictate, or mandate, or implement
Sony's policy for the PlayStation 4 seems similar to that of the PlayStation 3: publishers were allowed freedom over what methods they used to control gamers, such as using online passes to restrict the playing of used games. While technically this means that publishers could implement persistent online checks for their games, it's unlikely they will do so right away.
When clarifying the statement, Sony specifically said that it would "not dictate the online used game strategy (the ability to play used games online) of its publishing partners", although they reiterated that used disc-based games can be traded-in or sold at will despite their policy for third parties. Sony announced at their E3 2013 press conference that the console will be friendly towards used games, which was met with huge applause from the audience.