An Identicard is a personal electronic identity document used by the Earth Alliance that stores the owner's image, personal details, genetic fingerprint, passport, visas, security clearances, etc. Each card has a specific Identicard Number and is updated every time it passes though a computer check.
Earthforce personnel are issued special security identicards that grants them access to areas off limits to civilians and in the case of Security personnel, the authority to override security locks on personal quarters. When an individual resigns, or otherwise leaves the service they are required to handover their military identicard and procure a new civilian ID.
Identicards can only be issued by Earthgov, via authorised agencies. However when Mars was declared a free and independent planet within the Alliance in late 2261, the former colony gained the right to produce their own Identicards, currency and passports, at least in theory. In practice certain parties in Earthdome delayed putting the new Martian data into the system in order to force Mars citizens into using Earth documentation because it wasn't worth the trouble. To counter this, ISA President Sheridan offers the Interstellar Alliance's help by suggesting they set up a diplomatic office on Minbar and help the Mars Provisional Government establish an account outside Earth's jurisdiction.
Identicards are designed to be forgery proof as they must be matched to the genetic code of the owner. However, identity theft can be done providing the vendor accepting the card doesn't ask any questions or check the DNA profile against the owner, it can pass unnoticed for a time.