> we can't keep litigating the past forever
It's worth pointing out this reasoning is usually considered self-evident. I've rarely seen anyone doing any kind of deepdive into a practical reason for this.
There are only two broad outcomes, either things stay as they are, or much of the US is returned any remaining descendents of various treaty signatories.
The first is effectively a waste of time, the second a messy descent into hell on all sides.
As a parent of young children it rarely makes sense to litigate anything that happened more than 10 minutes ago, so perhaps people extrapolate from there :-) I'd enjoy that deep dive, though.
I mean, there are very valid reasons behind it.
People are not expected to hold onto there documents forever, humans forget.. and change
Figuring out what happened 3 years ago is hard, figuring out what happened 30 years ago is near impossible & often wrong
Litigating events that happened years ago is often impractical. Records are hard to find, memories are poor, witnesses are hard to find or dead, etc.
I think you argue for why don't you let the case be opened and then dismiss it in case there's not enough evidence available. On one level that's not great because it results in a lot of cases opened and then closed for lack of evidence. On another, it's not great because there's significant unfairness when some of these cases are pursuable and some are not --- drawing a line in the sand and giving a specific time frame for things to happen or not seems more fair to me, but I guess it's debatable.
Having unlimited time to litigate also suggests everyone should retain all records forever. That's a very high burden. A statute of limitations of say 3 years for contracts means I can discard old records at my own discretion without worrying that it may result in future liability.
Personally, I have some debts for services rendered where despite my desire and ability to pay, I've been unable to reach the service provider and pay them. I've also got some similar age debts where I certainly did pay them, but I've lost records of payment and it's been long enough that I might not be assured that I did pay them... sometimes things slip through the cracks. A statute of limitations means that my estate (and therefore my heirs) don't have to pay back the heirs of said service providers when they look through records and don't find evidence of payment.