Historically, FISC has been a rubber stamp. Unshockingly, they are still a rubber stamp.
https://epic.org/privacy/wiretap/stats/fisa_stats.html#backgroundAs you can see from above statistics, from 1979 until 2002 exactly zero requests were denied. Since 2002, five years had some denied (2003 - 4, 2006 - 1, 2007- 4, 2008 -1 , 2009 -2) while six years had zero. 2015 can be closed out with another satisfactory zero requests denied. Mind you, this is with thousands of submitted warrants. Each individual warrant could be targeted, or it could request entire databases of information. An example would be the NSA asking for "All call detail records or “telephony metadata” created by Verizon for communications (i) between the United States and abroad; or (ii) wholly within the United States, including local telephone calls." So a single warrant could be every telephone call in the entire country. That was a real example of a rubber stamped FISC warrant.
http://www.zdnet.com/article/us-spy-court-didnt-reject-a-single-secret-government-demand-for-data/http://www.theguardian.com/law/2016/apr/30/fisa-court-foreign-intelligence-surveillance-fbi-nsa-applicationsOne important thing to remember is that those numbers are just warrants. National security letters number in the tens of thousands per year. They are administrative subpoenas, and are not approved by a judge. They virtually always come with nondisclosure requirement, aka a 'gag order', which prohibits the party from disclosing that they are being served with a subpoena. NSLs can only cover metadata. That is dates, transactional records and phone numbers dialed. Not the content of telephone calls or e-mails. Of course, a government audit found that the FBI violated its liberal authority well over a thousand times, but the FBI has promised to not do that in the future. There is little to no oversight to ensure such, of course.
But so what? Obviously this is only used against foreign parties? Well no, dispute the name, FISC can be used against US citizens and regularly is.
And thanks to more recent news, it does not have to be restricted to terrorism, foreign intelligence or whatnot.
https://www.eff.org/deeplinks/2016/04/secret-court-takes-another-bite-out-fourth-amendmenthttps://www.dni.gov/files/documents/20151106-702Mem_Opinion_Order_for_Public_Release.pdfBasically, NSA's warrantless spying and wiretapping has been formally approved for use in general criminal investigations. As the EFF put it: FISC court decided that, instead of determining whether the Fourth Amendment was violated by the specific use of NSA collected information against particular Americans in criminal investigations, it only had to determine whether the program "as a whole" violated the Fourth Amendment.
So, as long as a program is found to more or less not violate the Fourth Amendment, it's kosher to be used to spy on Americans for general criminal investigations and give info to domestic law enforcement agencies.