Depends on whether you have a service relationship with a third party and they are providing a service or you rolled your own. If, for example, I paid a third party company for consultants to write some code for me but they provided source code they didn't have the right to, I think I should be able to hold them accountable for that. Whether it's a person or some automated process doesn't change that IMO.
I expect a court case would be used to determine what a normal person could expect, what was represented buy the consultant company, and what exactly I requested to determine how much fault each party has.
Everybody whose rights were infringed. The GPL often technically makes that "everybody else" by granting what were otherwise exclusive rights (to make and distribute copies) to everybody and then taking them away from infringers.
So e.g. Company X makes a GPL'd program to do A, but Company Y just copy pastes it into famous product P and acts as though they made it and obviously doesn't give out source. As a random person who doesn't even own P, the argument would be that technically the GPL says you should be able to get source code for the program from Y, even though you didn't buy their product P - you were harmed by their refusal to do what the GPL requires, so you can sue them.
Now, suing is probably not a good idea in this case, a court is likely to either insist you aren't really injured or that they can't help you, or both, but I think it could work at least in theory.
> the argument would be that technically the GPL says you should be able to get source code for the program from Y, even though you didn't buy their product P - you were harmed by their refusal to do what the GPL requires, so you can sue them.
I don't think that's the case. Whenever I see discussion about GPL violations, the copyright holder is the one who has to go after the violator (and often getting them to do something is difficult, because legal challenges can be expensive); the consensus seems to be that users who receive the software in a manner not compliant with the GPL don't have standing to sue. I'm not sure if a user has ever tried, though, so not sure if this has been tested in court.
SFC versus Vizio is exactly what you say doesn't exist. The SFC deliberately brought a case where they don't own the copyright, and says they are harmed and here's why the court should find for them.
I assume that's because even if they aren't the original rights holder, they still have standing because they (as the public) were given rights under the GPL implicitly by anyone using the GPL, for the GPL covered items. Since they were denied those rights, they were harmed, and thus have standing.
At least that would be my "layman that finds court cases and discussions of them interesting so consumes that as entertainment fairly regularly" best guess.
I mean if you are held accountable for using copyrighted code by the owner, you should then in turn be able to hold the consultant accountable for being the source of it, and the blame and responsibility may be shifted in part or in whole.
I don't think it's all that different than if I'm an employer and my employee does something illegal. An investigation can be made as to whether the acted on their own acted based on what the directions or prevailing understanding was at the company. That may change who is responsible in part or in whole and what steps need to be taken to provide recompense to those impacted by that illegal activity.
Every situation will be complex and unique in its own way. That's what courts are for, determining the unique aspects of a case and making specific ruling based on the law and the situation, as the judge (in determining what is acceptable and willing to be seen) and jury (to determine whether someone needs to be held accountable and to a degree how) see fit.
I expect a court case would be used to determine what a normal person could expect, what was represented buy the consultant company, and what exactly I requested to determine how much fault each party has.