LONDON — The criminal justice systems in Britain and Japan have flaws, but there are worse systems.

The British criminal justice system is based on common law. Despite attempts by governments over the years to undermine the basic rights of British citizens the judicial system is generally fair and justice is largely administered without fear or favor. Current issues arise from the threats from international terrorism, from the growth in gun and knife crime, and from anti-social behavior resulting from misuse of drugs and alcohol, lack of parental discipline and gang culture.

The threat from international terrorism has increased since the beginning of the Iraq war. The response of the government under pressure from the police and the security services has been to introduce Draconian measures to curb the activities of potential terrorists and to increase surveillance. Some of the measures taken have probably been unavoidable, but it sometimes seems that the government’s response does not take account of the danger that in undermining individual liberties they may be playing into the hands of the terrorists.

A fundamental principle of English law is contained in the Habeas Corpus Act, which dates back to the 17th century and which requires that no one shall be kept in custody, except by due process of law, and that an arrested person must be charged and brought before a court within a specified period. This used to be 24 hours but, in the case of people suspected of terrorist offenses, has been extended to 28 days. The government wants to extend this period but has so far failed to demonstrate that an extension is necessary. A small number of people suspected of plotting terrorist acts were interned without trial, but in the absence of adequate evidence the courts have ordered their release.

Another basic principle is that of trial by jury. The government has attempted to limit the role of juries and, in particular, have tried to abolish juries in the complicated cases of fraud. So far Parliament is rejecting its argument.

One principle of English law, which declared that no one could be tried twice for the same offense, has been overturned. When new evidence is found, a retrial can be ordered. So far there have been few such cases, not least because the judiciary keep a close eye on government attempts to undermine basic liberties.

In recent years British judges have been widely criticized by government ministers and in the media for being too lenient on criminals and handing out sentences that the public considers too soft. But the judges do have to take into account considerations that may not be obvious to those not present at court hearings.

They also have to bear in mind that British prisons are overcrowded and do not provide adequate education and rehabilitation. Prison reform is urgently needed but perhaps inevitably comes fairly low in the list of government priorities.

The British image of criminal justice in Japan has been colored by the murder some years ago of hostess Lucy Blackman and more recently that of Lindsay Hawker, a young girl teaching English. In the reporting of these cases the Japanese police do not emerge with an enhanced reputation. In the Hawker case the police seem to have been singularly inept in letting the prime suspect escape.

In the case of Blackman, Japanese criminal justice has been exceptionally drawn out, and fears have been expressed that Joji Obara, already convicted of multiple rapes, may not be found guilty of the dismemberment of Blackman.

These cases have drawn attention to other disturbing aspects of the Japanese criminal justice system. The image is of a system where the emphasis is on obtaining confessions of guilt through long hours of questioning and for an astounding conviction rate of 99 percent.

This raises the question of whether some innocent individuals are persuaded to confess to crimes which they did not commit, as well as doubts about the methods used to extract confessions — especially since defendants are not in a position to demand that their legal representatives are present during interrogation.

In Britain, judges are appointed from among practicing lawyers. In Japan, judges are professional civil servants who have not necessarily had previous court experience.

It is to be hoped that the introduction next year of juries of six lay assessors and three judges will help to ensure that not only is justice done but is seen to be done.

The reputation of British prisons may not be high, but the accounts of foreign observers suggest that conditions in Japanese prisons are often inhumane. Britain abolished the death penalty many decades ago and no country in the European Union preserves the death penalty. There is little doubt that where the death penalty is retained some innocent people may be executed. Surveys have shown that the death penalty does not act as the deterrent that its advocates argue is its main justification. The argument that the death penalty is an act of revenge by society to avoid personal vendettas seems to Western observers a throwback to feudalism. Japan’s retention of the death penalty and the way in which it is secretly carried out harms Japan’s international image.

There seems to be growing opposition to the retention of the death penalty in the United States not least because it may lead to the execution of innocent people. So long as Japan retains the death penalty it is liable to be seen as being in the same category as China and Saudi Arabia, where executions are frequent.

Hugh Cortazzi, a former British career diplomat, served as ambassador to Japan from 1980 to 1984.