Sunny Day

A state’s constitution produces direct legal effects only within that state’s territory. Acts committed online fall within the jurisdiction of the country where the victim resides, as the harmful effects of the offense are realized on that state's territory. I will not reiterate what has already been established.
Accordingly, the United States Constitution and the First Amendment do not apply extraterritorially and cannot displace the application of foreign law. They guarantee constitutional protections within the U.S. legal order, but do not prevent other states from applying their own laws to conduct falling within their jurisdiction. Consequently, even in the case of a U.S. citizen, since the relevant conduct falls within the jurisdiction of South Korea, South Korean law applies.
By way of illustration, an American citizen driving on a highway in Japan at 130 km/h (a speed that is lawful in his home country) will be sanctioned by Japanese authorities, because Japan’s legal speed limit is 100–110 km/h. He cannot rely on his domestic law and remains subject to Japanese law. Just as physical presence binds a driver to local traffic laws, the generation of severe financial and psychological harm within a territory establishes absolute jurisdiction over the offense, as a crime is legally committed where its destructive effects are realized.
You are conflating two distinct matters: on the one hand, the adjudication and sanctioning of the underlying act, which form part of the process of obtaining a judgment; on the other hand, the enforcement of that judgment, which constitutes a separate phase governed by the rules of compulsory execution.
Furthermore, to the extent that the acts may be classified in both legal systems as criminal offenses, specifically under cyberstalking provisions where the ongoing psychological danger to the victim could expedite emergency disclosure and enforcement procedures, the requirement of dual criminality may be satisfied, potentially facilitating international criminal cooperation at the enforcement stage.
Moreover, not every user who posts such messages is from the United States, which is precisely why I previously referred to the applicable international conventions.
In essence, information regarding individuals who publish online content that amounts to defamation, dissemination of false information, or harassment is obtained across jurisdictions, including from the United States, where most major platforms are headquartered. The responsible individual will therefore be held liable, regardless of their American citizenship.
Such cases will arise in the near future and will prove instructive; we await, for example, the outcome of the proceedings involving Choi Siwon and IU.

Excellent, keep it up.

More and more celebrities are taking legal action against online defamation and harassment. Following Choi Siwon's footsteps, IU has filed a request in the United States to uncover the identities of her online attackers, while fans of Kim Soo-hyun have also initiated an early-stage action against malicious comments.
Slowly, slowly we will have case law regarding such cases.
http://www.the-biz.co.kr/news/articleView.html?idxno=724631

Under international treaties and conventions, criminal or civil liability for acts committed online is generally governed by the law of the jurisdiction where the harm occurs, in this case, South Korea, where the alleged defamation or injury to reputation would be actionable. This principle applies regardless of the perpetrator's country of residence or the applicable legislation there.
When identifying anonymous users who post on digital platforms, the standard legal mechanism involves filing a lawsuit against the platform itself to compel disclosure of user data. This procedure has been successfully employed in South Korea by public figures such as Choi Siwon and now IU.
The relevant international frameworks facilitating cross-border cooperation in such matters include the Budapest Convention on Cybercrime and various mutual legal assistance treaties, such as Hanoi Convention, or Rome Convention.
Even where a state is not a party to such conventions, foreign litigants may still obtain evidence, for example, U.S.-based platforms through 28 U.S.C. § 1782, which authorizes U.S. federal courts to order companies within their jurisdiction (such as Meta, Google, or X) to produce evidence for use in foreign proceedings.
In practice, such disputes frequently result in civil remedies, including compensatory damages, which serve both as redress and as a deterrent against future misconduct.
Therefore, the commission of acts in the online environment that may constitute defamation, harassment, or threats can be sanctioned without the user being able to hide.

Actually, you didn't answer my questions. I'll repeat them, in the hope of receiving an intelligible response this time. I will add some more, since you made several affirmations in your message addressed to me.
How do you know whether @Kaelith's affirmation that Kim Soo Hyun is innocent is correct or incorrect? On what factual basis can you make that determination?
Please explain precisely:
- What does "the absence of a criminal case or conviction" mean in this specific context?
- What exactly do you claim "objectively happened"?
- On what basis is that assertion made?
Please define:
- What do you mean by "legal status"?
- What do you mean by "factual conclusions"?
- Under what circumstances do they interfere, and under what circumstances do they not?
When you say you were "pointing out the legal distinction being overlooked," which legal distinction, exactly, are you referring to? Invoking a "legal distinction" without defining it creates the impression of authority without substance.
Finally, can we legitimately claim that someone's affirmation is wrong if we ourselves do not know what actually happened? If yes, on what logical basis?
Please don't make another theory, just anser to my questions.

Prevention is preferable. I don't think such messages bother anyone, and if they are ignored, why should we comment?

When you tell someone they're wrong, you also tell them why.
Can you clarify what you mean when you state that “the absence of a criminal case or conviction does not, in itself, establish what objectively happened”? What exactly do you claim “objectively happened,” and on what basis is that assertion made?
Also, what distinction do you make between legal status and factual conclusions, and what would be your conclusion after making this distinction? Maybe that's how someone understands this mix of ideas, concepts and opinions.

How do you know if her/his statement about somebody's innocence is incorrect or not? I'm really curious!

The current situation is clear enough, the youtuber was arrested for defamation by spreading false information. In such cases, the investigation consists precisely in establishing whether or not the statement made by the youtuber is true. Analyzing what the youtuber stated and what the court's decision is now regarding his preventive arrest motivated by the safety of society, you can draw your own conclusion.

This is a correct information. Because the targeted cyberbullies utilized major U.S. based social media networks their actual identities were shielded by American privacy policies, leaving South Korean investigators unable to identify them to serve the lawsuit. To bypass this hurdle, the legal team filed an ex parte application in the United States using Section 1782.
The California federal court approved the order, forcing X Corp and Google to yield identifying data for the 10 account operators, including legal names, physical addresses and associated email addresses and contact numbers.
With personal data now exposed to the legal team, the South Korean civil lawsuit will set an important precedent for such cases.

Although legislation differs from one country to another, there are international and regional treaties that regulate cybercrime. The most recent global treaty is the Hanoi Convention – the United Nations Convention against Cybercrime.
These treaties and conventions establish legal provisions not only regarding cyber offenses themselves, but also concerning jurisdiction and the procedures applicable to offenses involving cross-border elements.

It's an excellent investigative program, a must-watch!

Exactly!

You did the right thing, even if it doesn't seem to have any effect right now. When the first punished case of cyberbullying on any platform is publicized and when it is observed that other interlocutors in the online environment take a stand, these cyberbullying activities will also become rare.

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I have the same information about collecting hateful comments as evidence, but also the fact that complaints are already being filed for some of them.

In fact, it is a fairly concrete text, well structured enough and showing the legal implications that irresponsible actions in the online environment can have. Moreover, in the future, this area will be better regulated because online violence has become a concern for all states. The rapidity of technological development has created a gap in the legislative system, but every year the legal provisions are completed to cover all online crimes.

I can't help but clarify when I see such errors. It was the least that needed to be said.

This should have been reported to the proper authorities.

That's a good question. I feel like we're living in apocalyptic times where moderators have disappeared.