Strong guidelines need to be established first.

The National Police Agency is going ahead with plans to create a nationwide database of DNA types taken from arrested people. The aim is to identify suspects by matching DNA types taken from blood, hair and other tissue samples found at crime scenes.

DNA is a record of genetic information, and the inner structure can be read like a sequence of letters. Within the sequence, there would be several sections with a specific pattern of alphabet combinations, and the frequency with which this occurs differs from person to person.

DNA types are groupings according to these combination frequencies.

Using the current classification method, the odds of two same people sharing the same DNA type is 180 million to 1. The method is also used to determine parental connections.

In criminal investigations, the main method of identifying an individual is through fingerprints. Under the law of criminal procedure, everyone arrested has their fingerprints taken. At the moment, there is a computerized database with the fingerprints of 8 million people that police forces up and down the country can scan.

Even without fingerprints, blood stains or hair strands left at a crime scene can determine a perpetrator's DNA type. But unless there is a DNA database of past offenders, there can be no ID matching system.

The police in this country already take blood samples from arrested people to determine DNA types, and match them with blood stains found at crime scenes. Each time the police take a blood sample, judicial authorization is necessary. Last year, DNA type analysis was used in over 1,000 criminal investigations.

These DNA type records are kept and maintained by the police headquarters of each prefecture. If that prefectural barrier is removed and a national database like the one for fingerprints is created, it would facilitate investigations enormously-especially in murder and rape cases, where blood and body fluids are more likely to be found at a crime scene. DNA type matchings would be a powerful tool in identifying criminals.

But there is a problem. Would everybody who is arrested have to give samples of their blood for the DNA database? Some say it's no different from having your fingerprints taken. On the other hand, some argue that it would be excessive to take blood samples from people arrested for minor offenses or unintentional traffic accidents.

Some people urge caution because the DNA can unfold reams of private information about a person.

The NPA maintains it will use not the entire DNA but only a portion for ID analysis. It says it will only use sections unrelated to the genetic sequence, record only the type codes, and discard the blood itself. By doing so, the NPA says there will be no infringement of an individual's privacy.

However, we need a law to define the parameters of the DNA database and to establish guidelines. It would be too uncertain and ambiguous to allow the police to take blood samples ``whenever necessary for investigative purposes.'' Also, it must be made clear that collected DNA types should be restricted solely to criminal investigations.

The experiences of foreign countries would be helpful. According to an Interpol survey of two years ago, 41 countries already have DNA type databases.

In Britain, the authorities take a blood sample after a person is convicted of a crime. The database now holds DNA type information of more than 2 million offenders. In Germany, a court has to determine that there is sufficient fear of the offender repeating a serious crime for the blood sample to be taken, and their database holds information on about 200,000 people.

In Japan, debate over this issue is just about to start. In order to protect society from crime, we need a system that the majority of people can accept.

-The Asahi Shimbun, Nov. 5(IHT/Asahi: November 6,2004)