Is it the approval rate? Is it the lack of transparency?
If it's the approval rate, in my experience the reason why court warrant approvals are so high is because intelligence / law enforcement are very risk adverse and will not submit requests that are likely to be rejected. Anecdotally, the officers I talked to considered it career poison to submit a request that got rejected by a court.
In a way I'm heartened by stories about NSA employees acting inappropriately, it means that they're being caught and disciplined and the Office of the Inspector General is doing its job. If it was routine and accepted it wouldn't be a newsworthy story and the inspector general.
That said, I don't think employee abuses have much bearing on the effectiveness of the FISA court as a source of judicial oversight for intelligence operations inside the United States.
Either the NSA is really accurate or something smells.
It also reflects that unlike other types of warrants the court can request revisions or additional information before making a decision and requests can be withdrawn before a formal rejection can take place.
Some estimates put the reject/withdrawal rate closer to 25%
Some more information: https://newrepublic.com/article/115257/fisa-warrants-court-t...
https://web.archive.org/web/20140402093319/http://www.uscour...