(Just for reference, this question is for a story I'm working on, and I wanted a realistic look at the law's side of things.)

So, a lot of fiction likes to play off the trope of a Vigilante. This person, (superhero or otherwise) often cuffs the baddies, and leaves them gift wrapped for the police, along with providing damning evidence to go with that. So my question is, does that actually help the police in any way?

These situations are almost always portrayed as:

  • Acquiring evidence without a warrant
  • Falsely imprisoning a person/criminal (This does not always involve the Vigilante seeing the crime happen, but they are usually acting like a police officer and pre-empting the crime.
  • The Vigilante is generally unable to be present for the accused to 'face their accuser'.

So, if evidence came from a known Vigilante, can it be used in a court of law?

  • 3
    The narrow legal question here – to what extent does the exclusionary rule apply to evidence which was illegally obtained by someone other than the government – is really interesting. I answered a general question about the scope of the exclusionary rule here; re-reading the passages I quoted, it does seem that the rule is limited to deterring government misconduct. This question seems likely to have come up in the case law, but I don’t have time to research it right now.
    – sjy
    Mar 14, 2018 at 3:26
  • 1
    @Raznarok, I just want to make sure, you're only asking about the vigilante trope and not about the very real ability to perform a citizens' arrest, correct?
    – A.fm.
    Mar 14, 2018 at 5:47
  • If I am interpreting what you are saying correctly, yes. I'm asking about the admissibility of evidence gathered unconventionally by a vigilante, as well as their ability to arrest someone who is not currently committing a crime, compared to an officer who can legally stop someone if they suspect a crime is being committed.
    – Razmode
    Mar 14, 2018 at 6:18
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    The point I wonder about is the ability of the defense to challenge evidence. "Yes your honor, these are my fingerprints in that gun. Before tying me up, the masked man gave that gun to me and forced me to hold it (if he was able to tie me it is obvious that I was under his complete control). And he took from my shirt the button that was found near the corpse." You (sorry, the vigilante) would need tamper proof evidence, or corroborating evidence.
    – SJuan76
    Mar 14, 2018 at 12:23
  • 1
    @sjy, typically evidence gathered by ordinary citizens (or, non-police officers) will be admissible, even if it would not be admissible if it was found in the same manner / under the same circumstances by a police officer.
    – A.fm.
    Mar 15, 2018 at 8:54

2 Answers 2


Can a vigilante perform an arrest?

This depends on whether the vigilante has the power to perform a citizen's arrest. The rules depend on the jurisdiction (and vary from state to state in the US), but generally the power to perform a citizen's arrest is quite limited. It may include the power to 'pre-empt' an offence if the would-be offender has attempted to commit the offence. However, often the power is limited to particularly serious offences (eg. felonies). There may also be a requirement that the crime occurred in the citizen's presence, or that the citizen was unable to contact the police instead.

Is evidence obtained by a vigilante admissible?

In the United States, the constitutional exclusionary rule generally prevents evidence from being admitted if the government obtained it illegally. I answered a general question about the scope of the exclusionary rule here. However, the Fourth Amendment exclusionary rule does not apply to evidence obtained illegally by a private individual: Burdeau v. McDowell, 256 U.S. 465 (1921).

In Burdeau, the defendant's papers had been stolen and turned over to the government, which proposed to present them as evidence to a grand jury. The Supreme Court said:

In the present case, the record clearly shows that no official of the federal government had anything to do with the wrongful seizure of the petitioner's property ... there was no invasion of the security afforded by the Fourth Amendment against unreasonable search and seizure, as whatever wrong was done was the act of individuals in taking the property of another ... We assume that petitioner has an unquestionable right of redress against those who illegally and wrongfully took his private property under the circumstances herein disclosed, but with such remedies we are not now concerned.

However, the exclusionary rule in some states goes beyond the Fourth Amendment. For example, article 38.23 of the Texas Code of Criminal Procedure provides that evidence illegally obtained 'by an officer or other person' is inadmissible. This provision was apparently enacted to deter vigilantes: Bubany and Cockerell, 'Excluding Criminal Evidence Texas-Style: Can Private Searches Poison the Fruit?' 12 Texas Tech Law Review 611 (1981), p 625.

Can such evidence be admitted even if the vigilante is not present?

Assuming that no exclusionary rule applies, evidence obtained by a vigilante can potentially be admitted through the testimony of a police officer or other witness, subject to the rule against hearsay and the question of reliability.

The rule against hearsay means that a police officer cannot give evidence that a vigilante told them that the accused was guilty. Evidence of this kind is not admissible because the accused has no opportunity to challenge the reliability of the source of the information in cross-examination.

The rule against hearsay does not apply when the probative value of the evidence does not depend on the truth of the absent vigilante's assertion. If the evidence provided by the vigilante is really 'damning' then it might fall into this category. For example, a vigilante might provide the police with a weapon that has the accused and victim's DNA on it, or tell the police that incriminating evidence can be found at a particular location.

A police officer can then give evidence that the weapon was tested and found to have matching DNA, or a search warrant was executed and the incriminating evidence was found. There is no admissibility issue here. However, the fact that the police were tipped off by a vigilante who has broken the law and is not present to face court may cause the jury to reject the evidence as unreliable (ie. it could have been planted).


Yes, they are useful to a police department

The vigilante gives the detectives a lot of useful practice in catching the vigilante and building a case against him, the patrol officers a lot of useful exercise chasing him down and the prosecutor a lot of useful judicial experience in seeing that he is properly tried and convicted.

He is also indirectly useful in that the "criminals" that the vigilante apprehended will still be on the street carrying out further crimes that will in themselves provide much useful experience for the police. Additionally, the crime that they were apprehended for will no longer take up police resources as it can now be filed in the "we know who did it but can never get a conviction" cabinet because none of the evidence they have will be admissible in court.

  • Is your answer "yes" to both the question in the title and the question in the body of the text? You don't seem to address the admissibility question.
    – user6726
    Mar 14, 2018 at 1:46
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    Not only unnecessarily snarky, but wrong. As long as the "vigilante" was not working under the direction of the government, the evidence a private citizen finds, even if it would otherwise be unconstitutional, will likely be admissible.
    – A.fm.
    Mar 14, 2018 at 6:01

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