ICAO publishes Doc 9303 Machine Readable Travel Documents, the technical standard for machine-readable passports. These contain biometrics to authenticate the identity of travellers.The passport's critical information is stored on a tiny RFID computer chip, much like information stored on smartcards.
On the whole, documents were not required for travel to sea ports, which were considered open trading points, but documents were required to travel inland from sea ports.
Certain legal tenets follow, namely: first, passports are issued in the name of the state; second, no person has a legal right to be issued a passport; third, each country's government, in exercising its executive discretion, has complete and unfettered discretion to refuse to issue or to revoke a passport; and fourth, that the latter discretion is not subject to judicial review. Under some circumstances some countries allow people to hold more than one passport document.
This may apply, for example, to people who travel a lot on business, and may need to have, say, a passport to travel on while another is awaiting a visa for another country.
Like some smartcards, the passport booklet design calls for an embedded contactless chip that is able to hold digital signature data to ensure the integrity of the passport and the biometric data.
Historically, legal authority to issue passports is founded on the exercise of each country's executive discretion (or Crown prerogative). Arkelian have argued that evolutions in both the constitutional law of democratic countries and the international law applicable to all countries now render those historical tenets both obsolete and unlawful.
Nehemiah 2:7-9, dating from approximately 450 BC, states that Nehemiah, an official serving King Artaxerxes I of Persia, asked permission to travel to Judea; the king granted leave and gave him a letter "to the governors beyond the river" requesting safe passage for him as he traveled through their lands.