Anyone within the intelligence community could have been able to "speak intelligently about it off the cuff'. It is clearly spelled out in Executive Order 12333
. Everyone within the intelligence community is given yearly reinforcement training on it.
The most important part that is emphasized during the training is that the US Intelligence Community cannot collect or maintain intelligence information on US citizens or those assumed to be US citizens (anyone physically in the US is considered a US citizen unless it is known that they are not) unless they are suspected of working for a foreign "entity".
Therefore, if that person is suspected or known to be working for a foreign entity, the information can be maintained.
There are no legal consequences if it's found that a US intelligence agency accidentally (or incidentally) collected information on a US citizen (think phone call between foreign person and US person), that information is purged from the system, and if related to a crime given to the FBI. There is only a legal consequence if the US continues to maintain the information once it's found and confirms that the US person doesn't fit the criteria in order to keep it. Keep in mind that most of the information that the NSA collects is never reviewed by a human and so isn't looked at to try and figure out if it involves a US person.
Also note that there is nothing that prohibits the US from giving the "incidentally" collected information to US allies who would, of course, share it with us at our request. The executive order only says that the US cannot maintain it.