IANAL but as I understand it, they need a FISA or regular federal search warrant if the data is collected for a "criminal investigation", but do not need a warr

IANAL but as I understand it, they need a FISA or regular federal search warrant if the data is collected for a "criminal investigation", but do not need a warrant if it was previously collected under a national security program. In a criminal case, they have up to 72 hours to get a warrant, if they give an actual wiretap order. This may be different in a "national security" investigation, where the PATRIOT Act is involved.