Civil law based systems are a more sane alternative to common law based system that relies on precedents. Law should be discussed in legislature and legislature must oversee and fix the law appropriately rather than make vague laws and leaving it to judges or others for interpretation. Due to not relying on precedents, the law is also easy to understand and apply and follow and enforce in civil law based systems. Cases also takes less time overall compared to common law based justice system.
Elected representatives are the authors or developers of law. Everyone else is users of law. Users cannot be allowed to change interpretation of law as anything other than how it is written.
Law made for horses and then vehicles got invented and law needs more clarity? Ask legislature to discuss and add new law for vehicles or modify existing law to also handle vehicles.
I think you're trying to hard to dismiss the justification here. There are certainly techniques for monitoring communications that use justifiably classified technologies that were probably developed to monitor communications of adversaries.
Imagine the use of which is helping keep American spies in Iran safe and the knowledge of the technique could help Iran identify those people. That's a perfectly reasonable classification of the technique.
What makes the interpretation of the law secret is that it mentions this hypothetical technology.
Imagine they have the technology to hear speech through walls passively using your WiFi signal. That technology is classified and they have the legal opinion that this doesn't violate the fourth amendment.
Wyden being concerned about whatever this is isn't surprising really but he's always on the extreme end of these interpretations, which I usually agree with, but judges typically don't agree with him.
I think it's probably generous to say the legal justification they are using has just as much chance of being legal as illegal. It would be nice to know what it was though because it can probably be defeated.
Wyden and others who are privy to what this is have made clear this is NOT about means or methods. This isn't about how the spying is done, it's about whether it's legal for the NSA to ever spy on U.S. citizens by ANY means. Existing law is very clear, it's absolutely not ever okay - no exceptions. It's completely irrelevant whether they're steaming open envelopes to read your junk mail or using a secret orbital mind-reading satellite to read your deepest private thoughts.
Experts like lawyers from the ACLU think it's something like a legal opinion which re-interprets the "absolute, no bulk spying on U.S. citizens ever" rule by claiming "it's not 'spying' if the govt pays a third-party commercial data collection service to give them the data voluntarily." That opens a backdoor for the govt to now back-link metadata and build one composite profile that includes all the private info the federal, state and local govt has ever had on you since birth (tax, employment, DMV, voting, school, govt assistance, Medicare, social security, etc) with everything any bank, credit card, or store knows about you, with every phone call, text, email and cell phone location ping you've had since 2014, with every bit of behavioral data Google, Facebook, LinkedIn, etc have about you.
To be clear, this is not "with probable cause they could get a warrant from a judge to send a supoena to each of those providers." This is something more like "they already have all that data in one searchable database but without this new secret legal opinion, as soon as it was clear the person was a U.S. citizen they could NOT look at it.
Now they can sit in a chair, and with just your phone number, email address, license plate or a facial ID match from a traffic camera to your driver's license, passport, Facebook profile or TSA airport photo, then instantly search for every single person you've communicated with in the past 3 years and every person they've communicated with and have an AI examine all that data from all those people and have a full 600 page report available in 15 seconds containing 7 million unique pieces of private data from 17,000 people that's instantly searchable - every email, every text, every purchase, every license plate scan, every location ping. No judge, no warrant, (and according to several recent reports), no record it ever happened, who did the search or under what pretext.
Everyone paying attention already knew it's been possible to do this for a decade. And everyone knows the government ALREADY does this for non-U.S. citizens. We just trusted that the government could not do it with U.S. citizens because the constitution and dozens of SCOTUS rulings make it so clearly ILLEGAL. But just like waterboarding and droning teenagers were once so clearly illegal, one secret legal opinion redefined "Spying" just like "Torture" was redefined in the 2000s and "Murder" was redefined in the 2010s - what the 4th Amendment has absolutely forbidden for 250 years instantly became legal to an invasive level Jefferson, Madison and Hamilton couldn't have dreamed in their worst nightmares.
It's about whether it's spying.
You have the law, you have precedent, best not to get on the naughty list.
There's a lot of stuff they do wrong but that isn't one of them. In this case, the Geneva convention was just written in a different time.