Emulators for seventh generation consoles aren't automatically legal like emulators for earlier consoles as that's when consoles started directly supporting DRM. Under the DMCA (and equivalent laws in other countries, which those countries are required to have to have a trade deal with the USA, which they're required to have if they want to participate in the global economy), devices that circumvent DRM are illegal, and obviously a seventh-generation-or-later console emulator has to circumvent the game's DRM to make the game playable on hardware other than what the DRM is attempting to restrict it to. The DMCA also added exceptions to itself when you're forced to violate copyright in some way to make different computer systems or software compatible with each other, e.g. if you need to reverse engineer something to figure out why it isn't currently working. While there's no settled case law yet, it's widely believed that the interoperability exceptions override the anti-DRM-circumvention-device parts. That still requires that the goal of the emulator is to make legally-owned copies of games compatible with new hardware rather than to circumvent DRM in not-legally-owned copies of games, and it's much easier to argue the former in court if you've not pirated anything and have been hostile to other people pirating things, so emulator developers who bother talking to lawyers are usually careful to make it clear that they don't support pirates and accumulate huge collections of disks and/or cartridges.