Japan: Criminal Procedure on Computer‐Related Crime

Publication Date01 Mar 1996
AuthorKiyoshi Yasutomi
SubjectAccounting & finance
Journal of Financial Crime Vol. 4 No. 1 International
Criminal Procedure on Computer-Related
Kiyoshi Yasutomi
By March 1989 approximately 400,000 general-
purpose computers were in use: these could be
found in various fields including financial systems,
traffic control, medicine, factories, official registra-
tion systems and so forth. It could be said that
more or less all important activities depended on
computers. Reflecting the wide-ranging computer-
isation of business quite a lot of computer-related
crime had appeared that could not be easily dealt
with under the provisions of the Japanese penal
code as then in force. So a bill to amend the penal
code was passed into law in the course of the
108th session of the Diet on 27th May, 1987. The
new Act contains provisions amending the penal
code so as better to cover computer-related crime.
These provisions came into force on 22nd June,
As a consequence it has become necessary to
study various procedural issues that pertain to
computer-related crime.
Nature of computer-related crime
Computer-related crimes have the following
(a) the subject-matter in question is not a tangible
entity but intangible data;
(b) computer processes are invisible and unintelli-
gible making it hard to observe the crimes in
(c) data is processed at such tremendous speed
that errors introduced illegally can quickly
spread so widely that it is difficult to identify
their source;
(d) data or a program used to effect a crime can be
easily eliminated after so destroying the
(e) a professional knowledge of computers is
required to investigate computer-related crime.
Therefore it is not easy to prevent a computer-
related crime from being committed whereas it is
relatively straightforward for computer engineers
and those with a professional knowledge of com-
puter systems to commit such crimes. Moreover
many computer-related crimes go undetected
because it is sometimes difficult for such crimes
once committed to be 'observed' and identified.
Warrant of search and seizure
Generally a warrant is required to obtain and pre-
serve documentary and other evidence before
search or seizure may be conducted. The require-
ment against unreasonable searches and seizures is
derived from Article 35 of the Japanese Constitu-
tion and is similar to the Fourth Amendment pro-
tection afforded by the US Constitution. The
nature of computer-related crime investigations
requires the search of a computer centre or a
remote computer terminal location and the seizure
of a computer or of computer-generated tangible
evidence if there is to be a successful prosecution.
Where it is necessary to gather as evidence system
guides, computer operational manuals, punch
program documentation, or documents on
how to input daily operational report data and pro-
grams or on computer printing types, we can say
that an investigation to verify whether or not they
are complete, original or duplicate, or legitimately
needed for the investigation, will be no different
from an ordinary investigation. As far as the pro-
gram documentation is concerned however, it is
indispensable to have a knowledge of the computer
program in order to understand the types and
scope of documentation such as source listings,
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