The use of electronic-based physical access cards to secure premises such as government buildings and large corporate offices has been in operation since the inception of bar code and magnetic-stripe cards in the 1970s. Over time, for secure access control, these first generation card technologies based on optical character recognition (OCR) and magnetic ink character recognition (MICR) were replaced by more sophisticated technologies such as smart cards and biometrics, containing encrypted data and techniques which were more difficult to dupe or to replicate \cite{michael2003a}.

An employee today wanting to gain access to their place of work, typically carries a photo identity card in addition to a contactless smart card based on radio-frequency technology, and may also use one of his/her unique physical characteristics (e.g.\ fingerprint, palmprint, iris or face) for verification. Generally, the more information sensitive the public or private enterprise, the greater the security measures introduced to safeguard against fraudulent activities. Card technologies, nonetheless, which are items carried by personnel can also be lost or stolen, and photograph identity badges can also be falsely replicated. This has led some innovators to consider the potential of radiofrequency identification (RFID) wearable or implantable devices for employee identification, with the added possibility of using wireless networks to do location fixes on employees in large premises (e.g.\ open cut mines or manufacturing plants). Automatic identification devices have the added capability of providing access to militarized zones, based on roles and privileges as defined by administrator access control matrices.

RFID implantables are theoretically not transferable and thus ensure a better level of security than traditional techniques. RFID implants are injected into the human body, in the same way that implants are injected into animals. Microchip implants come in the form of tags or transponders which contain an integrated circuit (see Figure~\ref{mm:fig:trans}. Animals have been implanted using the technology from the early 1990s to curb against disease outbreaks especially, and more recently for total farm management \cite{trevarthenmichael2007}. Registering your cat or dog by having it permanently microchipped for easy pet identification is now law in some states (e.g.\ the Companions Animal Act 1998 in the State of New South Wales in Australia).

Masters and Michael \cite{mastersmichael2007} define three types of application areas for human implantable microchips. These are (1) implants for control purposes (e.g.\ access control); (2) implants for convenience-oriented solutions (e.g.\ e-payment) and; (3) implants for care-related applications (e.g.\ looking up electronic health records remotely). A control-related human-centric application of RFID is any human use of an implanted RFID transponder that allows an implantee to have power over an aspect of their lives, or that allows a third party to have power over an implantee. A convenience-related humancentric application of RFID is any human use of an implanted RFID transponder that increases the ease with which tasks are performed. A care-related humancentric application of RFID is any human use of an implanted RFID transponder where function is associated with medicine, health or wellbeing \cite{michaelmasters2004}.

Steve Mann \cite{mann1998,mann2001} has placed microchip implants on his wearability axis in his published existentiality axis graph and distinguishes between implants owned and operated by the wearer (e.g.\ toothcam implants), to implants that are controlled by the issuer, to implants that are not removable by the bearer. He thus identifies the potential for varying levels of control but without alluding to newer forms of implantables for drug delivery or access control. Roger Clarke \cite{clarke1994} predicted very early on that it would be a matter of time before implantables in animals found themselves a human use function. Sitting on the extreme existentiality axis of the wearer where the bearer has no control, Clarke wrote: ``[i]n order to discourage uncooperative subjects from removing or disabling them [implants], it may be necessary for them to be installed in some delicate location, such as beside the heart or inside the gums.''

RFID bracelets have been used since the mid-1980s for home detention, extended supervision orders, prison inmate tracking and monitoring. Implantables are considered to have the added advantage of being discrete, in that they are not visible in outward bodily appearance. For example, parolees on extended supervision orders who might be implanted would be given the opportunity to undergo rehabilitation without the added stigmatization from observers for past felonies or misdemeanours \cite{michaelmichaelabbas2009}. Similarly, persons who have been charged with a crime but not yet tried or convicted could be granted bail and monitored electronically via the use of implantables, remaining innocent until proven guilty. In the same light, it is argued that if employees are implanted they may be less of a target for professional thieves, given that they cannot be identified as linked to corporation \emph{X} or \emph{Y}. For example, the theft of corporate laptops was highly prevalent around the peak of the \emph{dot.com} bubble, as professional thieves aimed to obtain and then on sell competitive intelligence on the black market. Those individuals well versed in the art of social engineering need only know the make-up of an identification badge to break through layers of physical protection to obtain company secrets, or to steal pieces of valuable equipment from the company premises. Even the wearing of corporately branded coveralls was not advised by regional security officers in large corporations, especially while traveling abroad for it distinguished employees as belonging to particular corporations, making them easy targets.