Suppose someone releases a Nintendo Switch emulator tomorrow, how much trouble is that individual in?

Emulation is considered legal -- we have had plenty of emulators of devices still covered by patents (varies but 20 years is a good bet), trademarks (can be indefinite) and copyright (well over 100 years at this point) so they would have gone that way if they could. The act of emulation is also held to be legal (interoperability is a big thing, the option to write your own code using one constitutes a very substantial non infringing use, even running games you own or have the right to run can be OK*) so there is that.

*this can depend upon how much DRM you have to go through to do it.

If the author obtained the specs or something illegitimately and used that to make an emulator there is scope for them to be slapped down. If they wrote it off the back of their own research, or other legit research, and were not bound by any other contract (all those "legit" developer SDKs Nintendo released to the world might well have had a clause saying no reverse engineering if you accept this) then absolutely free and clear to do what they like.

So yeah for the most part Nintendo is utterly powerless to do anything, and so they should be.

Thanks! That makes the picture a lot clearer

To be honest it doesn't matter if it's legal to do so. Nintendo has the money to take the person to court. Most likely the person wouldn't have the money for court fees or lawyers and would be forced to stop because they are unable to fight it.

But that hasn't happened with Cemu or Citra?

If they had the resources to come up with a working emulator in one day, sure they also have the resources to afford a lawyer or send a spaceship to mars. Hypothetically speaking.

Oh you mean Elon Musk ok

it depends if they use information that's only supposed to be available to nintendo

there's a little conspiracy on why cemu is closed source, as if they used classified information or something to develop it and made it open source, nintendo could cut open their wieners. Seeing how quickly cemu developed makes me a little suspicious if they took some documents from my boi reggie

If you're interested, look up, "Bleem!" - a PS1 emulator commercially released in 1999, well before online distribution was as ubiquitous as it is today.

Long story short: Sony took them to court, Sony lost, Bleem! went bankrupt due to legal fees.

(on a side note, I'm one of the few that actually bought a copy back in 1999 - my older brother wouldn't let me use his PlayStation, so I'd sneak his disks out of his room and play on my PC. )

From my shoddy 2 minutes spent on Wikipedia about Bleem, seems that they were commercialized and closed sourced hmm

True - but it answered the legal question, "Is emulation legal?" with a yes from the courts.

It also proved the homespun wisdom regarding patent law - the person with the deeper pockets wins, even if they technically lose. After all, Sony's here, Bleem! is not.

Regarding Switch emulation, I imagine it comes down to a simple formula for Nintendo board - which is greater, potential lost sales due to the technology, or the legal cost of fighting it?

It's business - it's always about the money.

So Nintendo doesn't care? Desmume, Dolphin, Citra, Cemu have never been challenged?