May evidence obtained by the Police be inadmissible?

Difficulty of regulation of investigation

In order to deal with crimes that employ emerging technology, the use of new methods of investigation is required. However, when considering that they could infringe or restrict some rights or interests of individuals, regulation of investigations is also required.

Obviously, in the course of an investigation, for example, it is permitted to search a residence and personal belongings without the consent of the person and even to seize personal property as evidence. Such an investigation that infringes or restricts the rights or interests of an individual without the consent of the person (compulsory investigation) cannot be carried out unless it is provided for by law (the principle of specific-legality requirement of compulsory measures.) Furthermore, when such a method is actually employed, a court-issued warrant is required as a general rule (the principle of warrant).

A warrant is not automatically issued when an investigation agency asks for one. In the case where the police search a house, for instance, the court examines the application for the warrant from the police, and the warrant will be issued only if the requirements for the search are satisfied.

As described above, one could say that double regulations from legislative and judicial perspectives are imposed on a compulsory investigation. As a rule, when a compulsory investigation can be avoided, methods other than compulsory investigation (non-compulsory investigation) must be used in the first instance (principle of non-compulsory investigation). In other words, measured regulations have been established to avoid the abuse of the authority of investigation.

In 2017, the Supreme Court of Japan ruled that a GPS monitoring investigation used in a case was illegal.

During the investigation into this case, the police did not regard this new method, a GPS monitoring investigation, as compulsory measure, and they carried it out without obtaining a warrant. The Supreme Court, however, declared that a GPS monitoring investigation falls under compulsory measure by its nature, and ruled that carrying it out without a warrant was illegal.

Moreover, the Supreme Court made it clear that a GPS monitoring investigation does not apply in any compulsory measures prescribed in current laws and that it is necessary to improve the legislation to use such an investigation.

As mentioned above, an investigation is not always conducted freely, and, if an investigation with new technology becomes an issue, it is not easy to make a judgment on whether such an investigation is lawful. Even when the police consider that a method other than a new one is taken lawfully, it may be found to be illegal as a matter of course.

Additionally, evidence obtained through an illegal investigation may even be inadmissible.

Illegal investigation and exclusionary rule

The exclusionary rule was an idea that originally existed in the United States. This is a rule whereby evidence that an investigation agency obtains through an illegal search will not be accepted in court. As one of several grounds for this, it has been considered that there is an expectation where an investigation agency will stop conducting an unlawful investigation if evidence cannot be accepted as a result of an unlawful investigation.

In fact, it goes without saying that you cannot do everything you want to in the name of investigation, and it can also be argued that this approach can prevent illegal investigations.

Most of you might think this is rational when you learn about this. Indeed, Japan has also adopted the exclusionary rule, and its district courts and high courts pointed out the illegality of investigation by investigation agencies and started to deny evidence obtained through such investigations relatively early on.

However, the Supreme Court of Japan theoretically recognized the exclusionary rule in 1978, and it was not until 2003 that the Supreme Court actually applied it to rule out such evidence, which is quite late compared to lower courts.

Since evidence is an important source for finding facts in criminal trials, fact finding may depend on whether the evidence is accepted or denied. As an extreme case, if denied evidence is the only incriminating evidence, it will be impossible to find a defendant guilty.

It is impermissible for investigation agencies to conduct illegal investigations. If an illegal investigation comes to light, it should also be impermissible for a court to find fact based on evidence obtained through such an investigation.

If such evidence is permissible, one can argue that a court, which makes a judgment on an impartial and independent ground, has a hand in the illegal conduct. This would undermine public confidence in courts.

On the other hand, if evidence is ruled out only because there is a minor procedural error by an investigation agency, many of those who are supposed to be convicted may not be punished or brought to justice.

For example, a police officer might commit a minor misconduct because they have a strong sense of mission to investigate a crime and collect evidence without fail or because they make a wrong decision in ever-changing situations of investigation.

If a court went strictly by the book to rule out evidence even if it was a minor misconduct, this would also undermine public confidence.

In fact, in the United States, the home to the exclusionary rule, there existed a judge who criticized this rule, questioning, “Should the criminal go free because the constable has blundered?”

Therefore, while the Supreme Court acknowledged the idea that evidence obtained through an illegal investigation may be excluded, it also expressed its view that evidence should be denied only if such offense is grave and it is considered reasonable to deny the evidence.

This illustrates the difficulty of a judgment to rule out evidence by applying the exclusionary rule.

What do you think of this rule?

Think of crime and investigation as your own problem instead of someone else’s

Most of you think that crime or investigation has nothing to do with you. The majority of people may certainly not commit a crime and become the subject of an investigation. As a matter of fact, however, there are cases where people have a hand in crime without realizing it.

For instance, there is an advertisement to give money to followers on social media. Mr. A applies for it and wins 20,000 yen. After he gives out his bank account number, 2,000,000 yen is deposited.

Then, he receives contact to give back the difference from the winning amount because there was a mistake in the transfer. Mr. A withdraws 1,980,000 yen and gives it to the person he meets at the designated place. Now, the person says that it is okay for Mr. A to give back only 1,900,000 yen to compensate for his trouble. On balance, Mr. A receives 100,000 yen, which makes him happy.

However, this person is a member of a fraud gang, which fished out the account number of Mr. A successfully to use his account so that Mr. B as a fraud victim could transfer money to it. As Mr. A withdrew the cash to give to the fraud gang, he is seen as a member of the gang and becomes a subject of the investigation.

It seems that the generations that have had the internet in their lives since they can remember especially believe all information on social media, which increases the risk of being involved in a crime.

In addition, if you publicize the fact that you are away on vacation or post photos of you naively, there will be a risk that a malevolent person breaks into your home or uses your personal information.

How would you find the response by the police if you found yourself in such a situation?

If you were deemed to be involved in a crime, you would not tolerate illegal investigation and believe evidence obtained through illegal investigation should be impermissible. While on the contrary, if you fell victim, you might hope that the perpetrator would be punished at any cost.

It is possible that an investigation method that is not currently used will be newly allowed by law. Whereas this is assuring, it could be misused.

As an assumption underlying the occasional judgment of courts that the evidence is not illegitimate enough to be excluded while recognizing the investigation as unlawful, there may be an intention to keep a balance among these different standpoints and to seek to sustain public confidence as mentioned earlier.

In that sense, I believe that it is crucial for us to take an interest in and give thought to outcomes of trials covered by the media.

We are usually unaware that investigation agencies and courts have a major role to make Japan a safe and secure society. Nevertheless, it is important to take an interest in topics related to crime and investigation in order to maintain such a society.

We might need to think of such a trend as our own problem instead of someone else’s.

* The information contained herein is current as of April 2023.
* The contents of articles on Meiji.net are based on the personal ideas and opinions of the author and do not indicate the official opinion of Meiji University.
* I work to achieve SDGs related to the educational and research themes that I am currently engaged in.

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