By wiretap I mean to also include interception of emails, instant messaging, phone calls, social networking messages, websites visited, and any similar modes.
According to the Wikipedia article for a 2008 amendment, the nsa is required to cease warrantless surveillance of a us citizen once s/he enters the U.S.
But there’s the chance that I’m not understanding the entire scope due to poor explanation or incorrect interpretation.
Asking about state agencies too.
TEchnically, any intercepts within the USA are subject to the 4th Amendment and the need for a warrant. Hence the “NSA can record anyone outside the USA”. Plus, the jurisdiction of the CIA/NSA etc. excludes the US; anything inside the country they are supposed to pass to the FBI. Part of the issue is tapping communications that originate outside the USA and terminate inside the country.
Of course, to avoid violating the letter of the law, the CIA/NSA can simply loan some tools to friendlies, like the British, and get them to do the intercept instead.
IIRC, the secret court which approves Patriot Act wiretaps has never declined to issue a warrant. Whether this is due to the applicatoins being carefully selected before being sent to the court, or the court being incredibly accomodating, who knows? (Remember that when the agents who arrested Moussaoui wanted further searches, they got push-back from the FBI HQ - but that was pre-Patriot aAct).
The secret court is the Foreign Intelligence Surveillance Court and it predates the Patriot Act by about 25 years.
They issue warrants to the FBI to tap communications within the United States for counterespionage and counterterrorism purposes.
It is a myth that they have never declined to issue warrants, although the number of outright rejections are very small. (But that’s true with ordinary search warrants in regular courts as well. It doesn’t take a lot to get a warrant.)