Locks that open due to being able to recognize the biometric data of a particular person were predicted by Robert Heinlein in some of his works. However, not too long, (less than twenty years) after he had envisioned it, locks that made use of Biometrics began appearing in many places. However, these early locks were often very unreliable, not to mention expensive. It would often take multiple tries before a print or an iris was positively recognized. However, they were useful enough and the concept was sound enough to improve upon, leading to several very much improved modern models that are not only more effective, but are cheaper as well.