Last week, the House Committee on Homeland Security held hearings on yet another “biometric exit” mandate. This mandate, like previous similar and unfulfilled statutory mandates, would require the use of biometrics to improve our ability to match traveler entrance-exit data. That is, we would, in theory, obtain more accurate information about which foreign travelers have left the United States.

The “Biometric Exit Improvement Act of 2013” would do that by requiring collection of fingerprints or other biometrics from travelers departing the country and matching them to biometrics obtained at arrival. More precisely, the law would require DHS to comply with a previous law, the “Intelligence Reform and Terrorism Prevention Act of 2004,” which required the establishment of a biometric exit system. Still more precisely, that 2004 law required adherence to several previous laws mandating development of biometric exit systems.

But this time, in 2013, the lawmakers really, really mean it. It’s almost like there is some sort of disconnect between the Hill and DHS. What might be the source of such a disconnect?

DHS, to which Congress appropriates a fixed amount of money each year, has to prioritize its myriad obligations. Given current budgetary constraints, DHS cannot do everything. DHS estimates that implementing a biometric exit solution just in airports (never mind the more complex situation at land ports) would cost at least $3 billion.

What’s more, DHS already has an exit system that matches data of exiting travelers with data of entering travelers with a high degree of accuracy. That is, DHS is already accomplishing what the unfulfilled biometric exit mandates require. It’s just that DHS is not relying solely on biometrics to do it. The biometric exit mandates accordingly remain unfulfilled.

Adding a system that collects biometrics from departing travelers might improve the accuracy of DHS’ efforts, but those involved in these efforts believe that the added accuracy would be very marginal. And DHS does not have the funds to spend on such marginal improvements. But pragmatism is not the reigning philosophy on the Hill these days.