Fingerprinting is the collection of patterns on the surface of the finger used for the purpose of identification. These patterns vary enough from individual to individual to make it possible, at least in ideal conditions, for one person to be distinguished from another on the basis of a fingerprint. The system has been part of criminal investigations worldwide for many decades, and the first fingerprinting for identity purposes occurred in the nineteenth century. Fingerprinting is not foolproof, however; smudged prints, for example, or finger ridges changing with age or injury can affect the ability of an expert to judge two prints to be from the same finger.
Fingerprinting is the best-known member of a class of techniques called biometrics, measuring an aspect of the body for purposes of identification. Other biometric methods exist, and have been becoming more common in recent years, but fingerprinting is still by far the most widely used.
Uses of fingerprinting
It is common for police to collect fingerprints at a crime scene and use them as evidence in trials. In many countries, fingerprints of convicted criminals are routinely taken and archived so that they can later be used in criminal investigations. There are both manual and computer-based techniques to facilitate finding a match quickly in a large database.
Criminals routinely do things to avoid leaving fingerprints. Examples include wearing gloves during a crime and wiping down a weapon after using it.
Registration of foreign nationals
Some countries take fingerprints from foreign nationals as a condition for entry, residence or employment.
Most foreign nationals are fingerprinted and photographed on each and every arrival in Japan; this information is held at a national level, and includes residents and non-residents alike. The data is compared to a blacklist of individuals who are to be denied entry, is taken at ports of entry only, and is held indefinitely. Refusal to submit fingerprints leads to denial of entry. Certain classes of foreign nationals are exempt: these include foreign diplomatic staff, 'Special Permanent Residents' (特別永住者 Tokubetsu Eijuusha), and members of the United States Forces Japan, who travel on military identity cards. Fingerprinting was re-started in 2007 having previously been abolished.
Foreign nationals who require a visa to enter the United Kingdom are fingerprinted in advance at a British embassy or consulate, and their prints compared to those on a blacklist. The prints are taken again on every arrival to confirm that the passport holder is the person who successfully applied for the visa. Citizens of the European Economic Arena and Switzerland, holders of 'right of abode' (permanent residency) and most diplomatic staff are exempted.
The USA fingerprints foreign nationals on every entry unless they have a 'green card' (permanent residency) or diplomatic status. Permit holders are also fingerprinted on first arrival. Visa applicants are also fingerprinted at the embassy or consulate on an initial interview.