Typically this is done via FISA warrants aside from that period during the Bush admin. China doesn't guarantee due process and get request information on anyone for any reason including dissidence. Every government will spy on their citizens to some degree, but that doesn't make them equivalent.
Just because most requests are granted doesn't mean that the court is a rubber stamp. It's just the opposite.
Most criminal indictments are also end in the state's favor, but that doesn't mean the jury system is rigged, it means that prosecutors don't bring cases that they are likely to lose. Similarly, the FBI doesn't apply for a FISA warrant unless they are certain its well warranted and the court's decision will be easy.
Regardless of how strong the government's case is, we have a right to face our accuser. The existence of the FISA court, and all its decisions, are, if not illegal, morally bankrupt. I don't care how strong the government's case against me is, I want and am entitled to my day in court. No quantity of legal talmudicry by government lawyers can change this fact, and therefore can't change any right-thinking person's mind that FISA, or anything like it, has no place in a democratic society.
A warrant is a warrant. An expression of the governments investigative powers.
The police aren't required to inform you and give you a chance to argue your case in court for why thy shouldn't raid your house for the drugs they're pretty sure you have.
Cops don't need your written permission to point speed radar at your car.
With a "real" warrant, I will eventually find out that it's been issued, either because I'll be served with it, or because the evidence will show up in court and the prosecutor will have to explain how they got it. It's totally possible that literally all people on Earth are currently being surveilled under a single FISA warrant, with any prosecutions in real courts being disguised by "parallel construction". We don't, can't, and probably won't ever know if this is the case.
FISA warrants are rarely denied because the intelligence agencies submit drafts to the court who tell them what is needed to get approval. Hence they never submit a warrant application that they aren't already assured will be approved. Anything insufficient is withdrawn before judgment.
Convenient, and perhaps legitimate, but not provably so. Courts are supposed to be adversarial, that's why we have prosecution vs. defense or grand jury. Judges are meant to be impartial arbiters. In the FISA system, judges play a dual role as both arbiter and defense, which is a conflict of interest.
It'd be a real court if there were a sort of public defender, and the judges simply mediated between both sides. You could see it working in the warrants rejected.
It is provably so. Namely if this is a serious interest I suggest you write to the House or Senate Select Permanent Committee on Intelligence [1] [2] and request documentation of such.
In fact the court is adversarial, though not like you seem to be envisioning. There are many courts in the US, in fact most where no litigation happens because it's inappropriate for the task. So the idea that they are playing "both sides" is a non sequitur.
The role of the court is to ensure that requests are legal and there is sufficient evidence to pursue the task as requested. It's exactly the same as when a judge issues a warrant.
Regardless of that, I think the greater concern is what it means for the rest of the world (the non-citizens). There is no reason to expect any sort of friendly/just process from foreign entities.
FISA warrants don't apply to this situation at all: they only apply within the US.
And even within the US, FISA warrants are only applicable to data collected which is intended to be presented in court. The CIA and NSA have no mandate whatsoever to gather data suitable for presentation in court, and investigatory agencies such as the FBI/DEA/ATF, which do have such a mandate, have lots of ways to launder evidence. In practice, FISA warrants are often issued long after the data has already been collected, and the FISA warrant is only requested as a means of laundering the evidence via one of the exceptions to fruit of the poisonous tree (parallel construction, inevitable discovery, or the good faith exception).
As it applies to this situation, I don't see any reason to believe the US is any less likely to spy on anyone than China. If you don't have the means to produce needed technologies yourself, then I'd choose the US or Chinese manufacturers based on other factors, such as cost, or which nation has incentives to use the data they collect against you.
