There is a difference between "guaranteed by law to have access to everything" and "has the prerequisite index and shape of data on hand with which to formulate queries capable of being answered such that access to the entire data space is possible".
The former is likely true. However, the lack of the latter, (which I assure you, is the case as SCI (Secret Compartmentalized Information) was developed specifically for that reason), sets an upper bound on the effective capabilities of anyone tasked with the job of oversight. You must be 10% smarter than that which you oversee to really do it effectively.
If you've ever chased down a memory leak, you'll understand what I mean. Senator Wyden cannot oversee the super secret Soylent Green program until somebody slips up enough to someone for word of a program that converts people to food to make it back to him to ask about.
The former is likely true. However, the lack of the latter, (which I assure you, is the case as SCI (Secret Compartmentalized Information) was developed specifically for that reason), sets an upper bound on the effective capabilities of anyone tasked with the job of oversight. You must be 10% smarter than that which you oversee to really do it effectively.
If you've ever chased down a memory leak, you'll understand what I mean. Senator Wyden cannot oversee the super secret Soylent Green program until somebody slips up enough to someone for word of a program that converts people to food to make it back to him to ask about.