Do you have a citation for that claim?
There are vast[1] systems in place that violate laws and norms, so much so the IETF has labeled pervasive monitoring as an "attack"[2]
[1] https://en.wikipedia.org/wiki/Global_surveillance_disclosure... [2] https://tools.ietf.org/html/rfc7258
"traditional warrant system" is not a legal term. FISA warrants are warrants. Highly problematic, but warrants.
You may be interested in reading about how even FISA felt the NSA overstepped:
https://www.vice.com/en_us/article/d7axey/this-is-the-secret...