Impossible in an the Orwellian system in which we currently live.
Agreed. Our beloved nanny-state's own rules state that the government agencies using/running the NICS database are prohibited from storing records on people applying to buy firearms, and yet how many times has the ATFE alone been busted for doing just that?
The "DNA database" they've been trying to construct - by swabbing down EVERYBODY who books into and holding facility for any amount of time, regardless of the charge - will be no different. Once they have it, there's no possible way they're giving it up.