It would be useful to have a court case be litigated all the way to the Supreme Court to establish the enforceability of the GPL whereby the defendant is forced to share code against their will.
This remedy of compelling a party to do something they agreed to do is called 'specific performance', and US courts only even consider doing this when real property (land) is involved.
For copyright infringement, generally what's available is injunctive relief preventing further infringement, disgorgement of profits, and statutory damages and attorneys fees as permitted by title 17. The injunction and disgorgement are the killers here that actually scare would-be infringers, and they mean that in most cases what you actually end up with is a settlement.
What if you host watch parties of the Real Housewives of Beverly Hills?
What if its address is on El Camino Real?
Courts force the sale of companies (etc) that don't involve real property. I think maybe they're reluctant and prefer monetary remedies but if what you say is correct that would neuter contracts pretty severely.
It would extend the right to repair to the software that we write.
Imagine if you pirated photoshop and the courts retroactively forced you to install Adobe spyware to comply with the license. Obviously the most the court could do is fine you or prevent further infringement.
Just because the plaintiffs aren't operating billion dollar businesses doesn't make their infringement claims less valid. The terms of the GPL explicitly spell out Deere's obligations. If they ignore them it converts to plain old copyright infringement with damages due for every illegal copy made.
I'm curious, what would that look like in this case (for a GPL violation)?
Do you need to track down every single person who contributed code under GPL and get them to agree?
Generally the way GPL has been in the courts, the suing party won't just take some money and walk away happy, they'll ask for the infringement to end (one way or the other). That would make other copyright holders happy too.
https://www.axios.com/2022/08/04/supreme-court-john-roberts-...
The Supreme court since FDR has been very resistant to role back the role of federal government, they have no problems smacking down state laws, but when it comes to rolling back federal laws or regulations well....
So here it would be determinative on which "side" the federal government chooses, or if the federal government stays silent which silence IMO is probably the most likely outcome for the federal government.
If they stay out of the fight, I think Deere Loses. If the federal government defends Deere then I think it is more 50/50
Even then, there's still the likelihood they are using GPL code/libraries above and beyond Linux itself.