Morally it's clear that you should treat others by the standards that you believe to be universal.
A government's ability to guarantee and protect these rights is, of course, limited by its geography. Other people may have different value systems which mean they protect a different set of rights than those defined in the US constitution (although the DoI does declare them to be 'unalienable'). But that's not what people are talking about when they talk about US government spying internationally. The US government violates rights it considers to be universal, and many of the people who's rights are violated are in countries with similarly enshrined values, and also who's countries are not at war with the US.
That's not to say there couldn't be ratified treaties between countries which give up some measure of sovereignty in order to set some better ground rules. We ratify all sorts of treaties like that, Obama ratified (by executive order, which I didn't know was possible) the Paris accord just last week. But I don't know of any treaties the US has signed to limit non-domestic wiretapping.
We covered some of this in our class on 'staatsinrichting' where not only the Dutch but also other important European countries organizations were discussed. This one stands out for me because it seems that at least one European country got this one exactly right.
Of course in practice things haven't always followed the theory. For example in French colonies, although indigenous people were supposed to enjoy the same protections than the French colonists, it didn't happen that way. The excuse was that they needed to be put "up to speed" first.
Of course, enforcing it is problematic because the USA is the most powerful country in the world and other governments are not keen on protecting their citizens' rights in this regard. On the contrary, they seem acutely envious of US surveillance powers and are trying to get some of them themselves.
For the record, I agree 100%.
Why would there be such an obligation for unlimited spying?
Spying is the cheapest and most effective way to provide for these goals.
How so?
In addition, spying can give a leg up to domestic commercial interests over foreign commercial interests.
Yes, Germany.
Almost all of German constitution applies to any "Person", not even just any human.
And the government has the constitutional requirement to help ensure those rights are granted to people globally.
Semantic point, do you differentiate between a "human" and "person"? This may be a translation issue, but to me there's no practical difference between the two.
The most famous example is the concept of corporate personhood.
See also : https://en.wikipedia.org/wiki/Personhood
Well, just in case Lt.Cmdr. Data ever comes to Germany ;)
This is my opinion, though a lot of it was shaped by the German education system, so it's definitely possible that when this question becomes actually relevant in a decade or two that a judge might rule this the official interpretation.
The most important basic rights are enjoyed by everyone.
Only citizens enjoy some basic rights (freedom of assembly, for example).
But there is a "catchall" basic right (Article 2, paragraph I) that can be used by non-citizens to claim those rights, as well.
The difference is that this catchall basic right is weaker when weighing it against conflicting basic rights (practical concordance) and it has imminent limitations (statutes can override it – although that must be useful and proportional).
Why does it apply this way? Think of the history of the Third Reich violating the rights of noncitizen nonnationals.
Secret services obey no law other than their own internal regulations, regardless of what people might see on TV series.
Charter of Fundamental Rights of the European Union protects you too! If you're non-US & non-Canadian, and use Facebook, then your data is under the control of Facebook Ireland Ltd, in Ireland. And the CFREU will protect you!