Nintendo Lawyer Spells It Out: An Emulator Can Become Illegal Depending On How It’s Used

A Nintendo attorney has shared a detailed explanation of why and how the company takes legal action against emulators.

Before we get into their statement, we feel the need to make our own introduction of sorts. You have likely mostly read vocal defenses of emulation before getting all the information about it. Let’s start real basic: Wiktionary defines an emulator as “A piece of software or hardware that simulates another system.”

While you often hear of emulators for older video game consoles, the term is not exclusive to video games. For programs made for the x64 architecture to run on an ARM Windows computer, the ARM computer has to emulate the x64.

We had previously stated that video game emulation lies in a legal grey area. What we meant there is that there are situations where it isn’t clear if a particular application of video game emulation is legal. Note that this does not come with any ethical or moral value judgement.

Now, when you are playing Kirby Tilt N’Tumble on your Nintendo Switch, the console not only emulates the Game Boy Color it originally ran on, but also its early motion controls, replacing the cartridge’s built in accelerometer with the Switch Joy-Con’s accelerometer and gyroscope. This is clearly legal emulation, and also executed to a degree most gamers can’t do on their own.

However, when you play the same game on your own PC or phone, using an emulator that Nintendo doesn’t own, would it still be legal? The Sony v. Connectix case created a precedent that makes emulation of video game consoles is legal, including copying its copyrighted BIOS.

No such precedent has been set for the games themselves. For now, all we know for sure is that there are copyright, patent, and trademark protections for video games, and those have been the subject of speculation on how to avoid crossing legal boundaries.

As reported by Automaton West, Koji Nishiura, patent attorney and deputy general manager of Nintendo’s intellectual property department, held a lecture at the Tokyo eSports Festa 2025 about this very topic. To quote Nishiura:

“To begin with, are emulators illegal or not? This is a point often debated. While you can’t immediately claim that an emulator is illegal in itself, it can become illegal depending on how it’s used.”

As Automaton West explains it, these are specific situations where using an emulator is illegal and which Nintendo have sought legal actions:

• If an emulator copies a program that ‘belongs’ to the game device it is emulating
• If an emulator disables encryption or other security mechanisms
• If an emulator links to sources of pirated games

There is some ambiguity on that first point, which we have to ascribe to limitations in translation. Because it clearly isn’t the case that every emulator that runs a program like the original hardware is illegal. Did Nishiura mean that emulators that make duplicates of programs become illegal? That sounds more likely, and it would also be more likely to have a legal precedent.

In any case, based on Nishiura’s explanation, Nintendo may not necessarily have a rulebook or Bible where they decide what kinds of emulation is legal or illegal. Instead, they’re defining their actions based on what laws already exist, and they also don’t seem to be looking for new loopholes or ways to make new definitions.

What we’re saying is Nintendo doesn’t seem to be as proactive in their efforts to stop emulation as the community believes. If it were, there would be no proliferation of Pandora’s Box style devices, and they may not even be a market for retro gaming handhelds. They could definitely have been more aggressive than they already are.

We know some gamers in the emulation community will be resistant to this analysis. We’re offering it as another perspective on the situation, as they may want to make better plans for any emulation related activity based on if they can better predict and anticipate what Nintendo would do.

We also shouldn’t forget that Nintendo isn’t the only game company going after emulation either. But on top of that, we now live in an age when the developers of popular free emulators go on to get hired by game companies to make those emulators for their games. Not every interaction the emulation community has with game companies has been hostile.

This should serve as a window to not only where Nintendo is on the subject of emulation, but on where video game emulation lies for the industry in general.