Can It Be a Crime to Publish Someone's Name Without Permission? Explaining Cases Where Personal Information Was Exposed

In today’s world, the spread of the internet and social media allows anyone to disseminate information with ease. At the same time, handling personal information now requires meticulous care. Many people want to know what criminal charges may apply if someone posts their name without permission. In practice, there are also many cases where people do not know how to respond when their name is exposed and simply leave the situation unaddressed.

This article explains the risks of leaving personal information—such as a name—posted without consent on the internet or social media. It also uses concrete examples to explain how to respond and what legal liability can be pursued.

Posting Someone’s Name Without Permission as an Infringement of Privacy Rights

Posting another person’s real name or other personal information on the internet or social media without consent, for the purpose of exposing it publicly, can constitute an infringement of privacy rights. Privacy rights are rights that everyone holds to prevent the unauthorized publication of information about their private life. They protect an individual’s private sphere and are regarded as an important human right that serves as the source of individual rights.

In Japan, privacy rights are understood as one of the fundamental human rights guaranteed by the interpretation of Article 13 of the Constitution of Japan, even though they are not expressly codified in statute. They have been established through constitutional interpretation and court precedents. Acts such as exposing someone’s name on the internet without consent intrude upon an individual’s private sphere and publicize private-life information, and therefore can constitute an infringement of privacy rights.

When Posting Someone’s Name Without Permission Becomes Illegal

An infringement of privacy rights does not, by itself, immediately amount to illegality giving rise to criminal punishment. However, depending on what is exposed and what is written together with the name, the conduct may not only infringe privacy rights but also fall under criminal offenses and attract penalties under Japan’s Penal Code.

Below, we explain situations where posting someone’s name on the internet without consent can lead to criminal liability, with examples of applicable provisions of Japan’s Penal Code.

Application of Penal Code in Cases of Defamation and Insult

If someone not only posts another person’s name on the internet or social media but also adds statements that defame or insult that person, then, in addition to infringing privacy rights, there is a risk of criminal punishment for defamation or insult under Japan’s Penal Code. Defamation (Penal Code, art. 230) is defined as follows:

“A person who defames another person by making allegations in public, regardless of whether such facts are true or false, is punished by imprisonment or imprisonment without work for not more than 3 years or a fine of not more than 500,000 yen.”

Furthermore, the crime of insult is defined as follows:

“A person who insults another person in public, irrespective of whether the accusation alleges facts or not, the person is punished by penal detention or a petty fine.”

In other words, where a person’s name is posted on the internet or social media without consent and that person is defamed or insulted in this public space, there is a possibility that criminal liability for defamation or insult will arise.

Revenge Porn

Posting a person’s sexual images or videos on the internet without consent, together with that person’s name, violates the Act on Preventing Harm That Is Due to Private Sexual Image Recordings Being Provided to Third Parties (commonly known as Japan’s Revenge Porn Prevention Act) and is subject to criminal penalties. The offense of so‑called revenge porn applies regardless of the victim’s gender, so men as well as women can be victims.

Related article: What is the Revenge Porn Law? Explaining the Penalties and How to Respond[ja]

Cases Where Exposing Personal Information Does Not Constitute a Crime

As noted above, posting someone else’s personal information, including a name, on the internet or social media without permission can in some circumstances amount to a crime. However, not every act of exposing personal information is criminal.

Where a post plainly contains defamatory wording or includes sexual images, it is relatively straightforward to see that the elements of an offense may be met. In contrast, there are many situations where it is difficult to determine whether the legal requirements for a crime are satisfied. Since an infringement of privacy rights alone does not immediately result in criminal penalties, it is necessary to carefully assess whether the conduct is in fact punishable.

Common Examples of Exposing Personal Information on the Internet and Social Media

This section explains practical examples, often seen on the internet and social media, of situations where other people’s personal information is exposed. Such conduct sometimes occurs in the heat of the moment or as a result of carelessness, but there are cases where exposing personal information in this way is unlawful.

Publishing Real Names Together with Defamatory Statements

If a person discloses someone else’s real name and, at the same time, posts statements that defame that person or lower the person’s social standing, criminal liability for defamation may arise. Examples of such posts include:

• 〇〇 has massive debts with consumer finance firms and is on the verge of bankruptcy.
• 〇〇 was arrested by the police in the past for theft.
• 〇〇 actually cannot study at all and failed every subject in exams, so they have been held back a year.

As these examples show, defamation can be established where someone’s real name is exposed and specific facts are publicly posted with the purpose of lowering that person’s social evaluation. Whether the posted content is true or false does not affect the establishment of defamation, but the facts alleged must have a certain level of specificity.

Publicizing Nuisance Conduct or Troubles

In recent years, there has been an increase in cases where people film instances of nuisance conduct or disputes and post them on social media platforms such as X (formerly Twitter) out of a sense of justice. Even if it is true that the other party engaged in nuisance behavior, depending on the content of the post, defamation may still be established.

Further, if images are posted that expose a person’s face without mosaic processing, not only the name but also the image may infringe privacy rights, and in some cases infringement of portrait rights can be alleged, allowing civil liability to be pursued.

Public Disclosure of Private Communications

Publicly disclosing one‑to‑one communications—such as direct messages (DMs) on social media, LINE messages, or emails—may, depending on the circumstances, give rise to liability.

The act of posting screenshots of such exchanges on the internet is not, by itself, automatically unlawful. However, where the disclosed content amounts to defamation, or where real names are shown without concealment in the course of exposing the messages, responsibility for that conduct may arise.

Difficult Cases in Assessing the Illegality of Exposing Personal Information

As discussed earlier, exposing personal information such as real names on the internet or social media can, in some cases, amount to defamation, revenge porn, or other criminal conduct. Even where no criminal penalty is imposed, civil liability may arise. At the same time, not every act of exposing personal information is illegal, and there are cases where it is very difficult to determine whether the conduct is unlawful

Exposing the Real Names of Individuals Who Operate Anonymously

Many influencers, authors, and similar individuals conduct their activities anonymously or under pen names without revealing their real names. Likewise, individuals working at host clubs, cabarets, and similar venues may work under pseudonyms. Where such individuals do not wish their real names to be known, disclosing those real names can constitute an infringement of privacy rights.

Exposing Partially Masked Real Names or Initials

If a person who usually acts anonymously has their name posted in a partially masked form or only as initials, that disclosure by itself does not necessarily amount to an infringement of privacy rights. This is because it is difficult to narrow down and identify a single specific individual from initials or partially obscured characters alone

However, if other related information is posted together with those masked names or initials so that the person can easily be identified, then it is treated the same as exposing the real name, and an infringement of privacy rights can be established. Furthermore, if the post also contains defamatory content, liability for defamation may arise.

Legal Liability That May Be Pursued When Personal Information Is Exposed on the Internet or Social Media

When personal information such as a real name is exposed on the internet or social media, there may not only be an infringement of privacy rights but also criminal penalties and claims for damages under civil law. This section explains what types of legal liability can be pursued if your name is posted and exposed online without your consent.

Criminal Liability Through Criminal Penalties

If the posted content includes defamatory or insulting statements, it may be possible to seek criminal penalties for defamation (Penal Code, art. 230) or insult (Penal Code, art. 231) under Japan’s Penal Code. Defamation is punishable by imprisonment with work for up to three years or a fine of up to 500,000 yen, while insult is punishable by detention or a petty fine.

Related article: What is the Offense of Insult? Examples of Specific Words and the Difference from Defamation Explained[ja]

Civil Liability Through Claims for Damages

If the person who exposed another’s personal information, such as a real name, on the internet can be identified, civil liability can be pursued and a claim for damages can be made. Civil liability is separate from criminal penalties, so even if no criminal punishment is imposed, a court may still order payment of damages. To identify who exposed the personal information, it is possible to use the legal procedure known as a “Demand for Disclosure of Sender Identification Information.”

Related article: What is a Disclosure of Sender Information Request? A Lawyer Explains the New Procedures Established by the Amendment and Their Process[ja]

Risks of Leaving Personal Information Exposure on the Internet or Social Media Unaddressed

When your personal information, such as your real name, is exposed on the internet or social media, it can be difficult to decide how to respond. If the content is clearly malicious, you may feel that you must take some action, whereas if the content does not seem particularly malicious and there is no obvious damage, you may be tempted to “wait and see.”

However, leaving personal information exposed on the internet—where anyone can easily view it—can lead to various risks.

False Information and Rumors Spread Beyond the Personal Data Itself

Leaving exposed personal information, such as a name, unaddressed can lead not only to ongoing exposure of that data but also to the spread of falsehoods and groundless statements about the person. There are cases where, once a name is exposed, people speculate and post unfounded rumors simply because part of the name matches that of another person.

For example, there has been a case where a person who had no connection to an incident suffered damage because groundless rumors spread online saying that they were the suspect in a road‑rage case, based solely on having the same surname as the suspect or living near the accident site. In that case, the company run by the victim was exposed on the internet as “the workplace run by the father of the road‑rage suspect,” together with its full address, resulting in a flood of protest calls from all over Japan.

Further Spread of Information Through Other Media

There is a risk that exposed personal information will not remain confined to the social media platform or bulletin board where it was first posted. Instead, there may be further posts on other platforms and sites, causing the information to spread more widely. As information is shared onto other social networks and sites, it can reach an even greater number of people, and the actual harm can become more serious, so caution is required.

Once personal information has spread across many platforms and sites, it becomes more difficult to respond, for example, by requesting deletion of posts. In addition, as more people see the information, the risk that new falsehoods or lies will be added increases.

Real‑World Harm from Harassment and Pranks

There is also an undeniable risk that, beyond your real name, your address, phone number, and other personal information will be exposed. This is particularly so in cases where unfounded rumors lead to someone being wrongly treated as a suspect in a case and the situation escalates to the point that their home and workplace details are published.

Once such information is disseminated, the affected person may suffer concrete harm, such as a deluge of prank calls, protest calls, and mail from across the country. This is extremely troublesome, ranging from calls driven by mere curiosity or a desire to play a prank to calls from people who believe the rumors and telephone to protest out of a mistaken sense of justice.

Impact on Major Life Events

Information published on the internet can be accessed by anyone, at any time, so it is always possible that exposed personal information will be seen by someone at a critical moment. Depending on the nature of what has been exposed, it may negatively affect major life events, such as marriage or employment. For those who see the information, it is generally impossible to verify whether the content is true, so the exposure can have harmful consequences regardless of its truth.

Risks to Personal Safety

If not only your real name but also your home address or workplace address are exposed, there is a risk that third parties may come to these locations, posing a direct threat to your safety. It is dangerous not only because the person who originally posted the information might appear, but also because other individuals who saw the information may come unannounced. If strangers come to your home, the danger extends beyond you personally to your family members as well.

How to Respond When Your Personal Information Is Exposed on the Internet or Social Media

When your personal information is exposed on the internet or social media, various risks may arise, and if left unaddressed, in the worst case it can endanger you or your family. It is therefore crucial to respond as early as possible. This section explains how to deal with the exposure of your personal information online.

Consult a Human Rights Consultation Service

Japan’s Ministry of Justice has established several consultation channels, including the telephone hotline “Everyone’s Human Rights 110” and the online “Internet Human Rights Consultation Reception.” If you face a risk of harm because your privacy rights have been infringed or your personal information has been exposed without consent, you should first consider consulting these services.

Request Deletion or Account Suspension from the Platform

If your personal information has been posted on social media or an online bulletin board, you can ask the operator or administrator of the platform to delete the post. You can also request suspension of the account that made the post; freezing the account of a user who makes malicious posts can help prevent secondary damage.

Consult the Police to Pursue Criminal Liability

Where the infringement of your privacy rights also involves defamatory content, you can consult the police and seek to pursue criminal liability. To pursue such liability, an investigation by law enforcement authorities is required, and this typically involves filing a damage report or a criminal complaint. For internet‑related problems, you can also contact the “Cybercrime Consultation Service” that the police have established.

Consult with a Lawyer to Pursue Civil Liability

Separately from criminal liability, you can also pursue civil liability and seek compensation for damages. To pursue civil claims, it is advisable to consult a lawyer, who is a legal professional.

Even where the identity of the person who posted your information is unknown, a lawyer can request disclosure of sender information and thereby help identify the poster. A lawyer can also advise you on important points to consider when pursuing civil liability and provide specialized support.

Summary: If Your Name or Personal Information Is Exposed, Consult First

Posting another person’s name or personal information on the internet or social media without consent constitutes an infringement of privacy rights and, depending on the content, may also give rise to criminal and civil liability. Even where there is no immediate harm when your name or other information first appears online without your permission, the future risks are unpredictable.

In the worst case, such exposure can lead to direct danger to you and your family. If your real name or other personal information has been posted without your consent, you should first consult a lawyer. By seeking advice at an early stage and taking appropriate measures, it is possible to prevent actual harm and avoid an escalation of damage.

Guidance on Measures Offered by Our Firm

Monolith Law Office is a law firm with strong capabilities in both IT—particularly the internet—and law. In recent years, reputational damage and defamation spread online have caused serious harm as a “digital tattoo.” Our firm provides solutions for dealing with such “digital tattoos.” Details are available in the article below.

Areas of practice at Monolith Law Office: Digital Tattoo[ja]