My client has disclosed to me that he is secretly a masked vigilante in a major metropolitan city in the state of New Jersey, United States. Under this identity, he stops crimes in progress and turns the perpetrators over to the local police.1

We are trying to determine whether or not these actions are illegal (there are concerns of corruption in the city's police department, so we cannot rely on their tacit approval of his behavior). Furthermore, we would like to make sure that the individuals that my client turns over to the police will not be able to escape justice due to the manner in which they were captured, so we would like to know if there are any major limitations to what he can do that he should be aware of.

1 We will neither confirm nor deny rumors of other activities, including property damage, fighting other costumed individuals over personal vendettas, or driving an unregistered car without a license.

  • 2
    The question is prompted by a fictional sci-fi character, but I am looking for answers based on real US law, rather than the fictional world he lives in. See Can an extra-terrestrial be legally adopted? for an example of this sort of question on the site. Commented Sep 19, 2017 at 0:12
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    I question the seriousness of this inquiry, but nevertheless, you’re going to want to simply look up the citizens arrest laws in your jurisdiction. Usually, they are legal, but there are restrictions on how much force one can use to apprehend an individual.
    – A.fm.
    Commented Sep 19, 2017 at 11:40
  • By the way, by virtue of being a form of vigilanteism, being a “vigilante” is not legal.
    – A.fm.
    Commented Sep 19, 2017 at 11:42
  • @A.fm. however, a bona fide Citizen's Arrest usually is legal, even though highly discouraged by pretty much everyone in law enforcement. Commented Sep 19, 2017 at 23:56
  • @RobertColumbia yep, that's what my first comment said.
    – A.fm.
    Commented Sep 20, 2017 at 0:26

2 Answers 2


There isn't a general answer to this question. It needs to be evaluated incident and sub-incident act by sub-incident act.

  1. The use of force is legally permitted to prevent harm to others and to the property of others under some circumstances.

  2. Citizens arrests are permitted under some circumstances, but generally, the person making the arrest must have personal knowledge of the crime while it is in the process of being committed.

  3. Some laws prohibit wearing masks under some circumstances, but usually not in all circumstances.

  4. Your client's "business model" is not consistent with being able to testify in court, so the criminal justice system will only be able to convict someone whom your client delivers to police if they can do so without your testimony.

  5. As a general rule, the 4th Amendment exclusionary rule does not apply to evidence collected by private parties or to statements obtained by private parties that are not made under duress that are not Mirandized. But, if your client is effectively "deputized" or becomes a "de facto" agent of the state who is called up to be a member of a posse for the police, for example, by using an agreed symbol such as shining a light with a symbol on it on some clouds, at that point, with respect to that matter, the 4th Amendment exclusionary rule and Miranda probably do apply to evidence that your client obtains, and exclusion of that kind of evidence could make prosecution much more difficult, unless the prosecution can successfully make an argument that the other evidence that the illegally obtained evidence leads them to is not "fruit of the poisonous tree" because it would have inevitably been discovered in due course using only the legally obtained evidence.

  6. Even if your client does violate the law, law enforcement is not obligated to investigate his alleged crimes even if the victims complain, and prosecutors are not obligated to prosecute those crimes, even if they have overwhelming evidence of guilt which they could use to secure a conviction. Prosecutorial discretion is basically absolute.

  7. Your client might be sued civilly for operating a corrupt enterprise under RICO, for various intentional torts, and for negligence, by people who think that they have been harmed by his conduct, but someone can only sue your client if they can figure out who he is and serve him with civil process.

  8. If you are helping your client conduct on ongoing criminal enterprise, whether or not the crimes are prosecuted by the criminal justice system, the attorney-client privilege you have with your client is probably forfeit should you be placed under a subpoena and your may be violating other ethical rules. But, of course, somebody has to figure out that you are part of this criminal enterprise before you suffer any consequences for being involved.

  • Regarding 7, couldn't they serve him without knowing his identity by handing him the documents after tracking him down in his masked state?
    – phoog
    Commented Oct 3, 2017 at 4:50
  • @phoog Suppose you serve him with a complaint and enter a default judgment. To whom do you send a garnishment? Upon what property do you serve a writ of execution?
    – ohwilleke
    Commented Oct 3, 2017 at 18:52
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    Perhaps the difficulty in prosecuting means the criminals get routine psych evals and trips to a mental institution instead?
    – fectin
    Commented Jul 1, 2021 at 12:47

The detention of criminals in the act is not necessarily illegal, there are methods and laws that prohibit things like weapons. Also your client would most likely be needed to testify in court unmasked. Depending on the nature of the crime your clients testimony may be the needed evidence for conviction. The real concern would be the criminal suing your client for damages in civil court.


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