Compliance with legal safeguards must be ensured through comprehensive and regular judicial oversight. Examining the effectiveness of data collection measures is equally important. Overseers need to know about this to assess the political value, the cost efficiency, and the need for the reauthorization of warrants. Identifying suitable metrics and methods for this remains a considerable challenge. For example, if data from a certain program or collection stream never feeds into the production of intelligence reports, does this mean that this particular data collection is superfluous and a strain on the limited resources of the intelligence community? Or, in contrast, would this be tantamount to someone cancelling a fire insurance policy simply because, thus far, his or her house has not caught fire?