I'm asking this hypothetical situation mostly as I was considering writing a story with the premise and want the story to be legally accurate, but also because I'm frankly curious how the law would handle such a situation.

Let's say someone (call him Bob) got sick of police being unable to act against individuals everyone 'knows' to be committing a crime due to lack of sufficient evidence to get a warrant. One day he decides to take matters into his own hands and he calls into 911 with a made up claim that he witnessed a crime take place and a gunman drag someone into a known crack house.

As I understand it when the police arrive they will have sufficient justification to enter the crack house without a warrant to intervene with a crime believed to be in progress. They won't find evidence of the original, made up, crime, but once they have entered the house they will likely see evidence of other crimes. Since they were there in good faith the evidence of other crimes within 'plain sight' in the house would be fair game and could be used to make arrests and/or get a warrant to search the rest of the house for more evidence. Despite the fraudulent nature of the original claim arrests could be made since Bob was not an agent of the police. So far this is covering legal concepts I think I understand.

Now lets say that the police were never able to trace the original fraudulent call to Bob, and Bob gets it in his head to act as a the world's least interesting vigilante. He starts regularly making fraudulent calls claiming to witness a crime in progress to the police to give them justification to enter locations that are commonly believed to have illegal activity within them in a hopes of helping the police to collect enough evidence to make arrests.

While Bob changes the number he is calling from and as much of his MO as he can each time the police would noticed a pattern of fraudulent claims and have reached the point that they can usually guess when a call is a fraudulent one made by Bob, but they can never be certain it's him or that a crime isn't actually happen. Assume the police have actively stated they do not support or condone Bob's actions, have made a public plea for him to stop, and are trying (but failing) to find and arrest Bob as well.

I assume the police would continue to respond to the claims in case the call is real and a crime is actively in progress. Is there a point where they would no longer possess sufficient cause to enter a premise to investigate a believed crime in progress due to their suspicion the crime may not be legitimate? If they do have justification to continue to enter the premises then at what point, if ever, would evidence witnessed as a result of responding to the potentially fraudulent calls not be admissible?


3 Answers 3


Calls to 911 are treated as genuine at all times until the complaint is dealt with. This is because most people only call 911 for legitimate reasons and even some criminals call 911 because they want them to know the situation (Bomb scares are an extreme version of this as they cause a lot of disruption; they cannot be ignored because if the cops were to call bullshit and it was proven not to be bullshit, it's gonna be a lot worse than if they treat it as real and find out it's an alarm clock.). From the point of view of the first responders, whether cops, fire, or EMS, the call is always real and to be treated as such.

Entering without warrant is legit if they have a probable cause of a crime or a person in distress, such as a hostage or a person in medical need; the emergency call is almost certainly sufficient. As you correctly said, at this point any evidence of a crime in plain sight is good reason to pursue the criminal acts unrelated to the original call. 911 calls are recorded so they can prove to the courts they got a tip and were following up.

However, tying up emergency services with fake crimes is still not a proper use of 911 and there are ways to find people making bogus calls. 911 also traces phone calls in case of prank callers or even generally locating people in distress (if the dispatcher has to tell someone who is hiding from robbers in her house to be quiet, they can still dispatch officers to the general area by pinging the phone's metadata) so a string of burners will be noticed. Burner numbers can be traced to point of sale and most stores that carry them will have cameras (staff that remembers, not so much). If using pay phones, in this day and age, again there is likely cameras because the frequency of the latter and the infrequency of the former. Phone Booths haven't been a thing for far longer, so much so that the Christopher Reeves Superman film had a famous gag about how Phone Booths were phased out, when Clark Kent, needing to switch to his iconic Persona, runs to a bank of payphones (all without booths) and desperately looks for a new place to shed his clothes... in the 1970s. Either way, cops would be looking for nearby cameras to identify you and without many pay phones reliably lying around it won't take long.

The more dangerous aspect of this is that drugs and organized crime are pretty much hand in hand. It could be the crack house you just called in is well known to the cops, but they're trying to use it to find out who the supplier is. The vigilante could be ruining their sting by calling in a true threat. If he does this too much, the local gang members will be looking out for him and may try to find him too; and whereas the police have rules, the gangs do not.

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    Yes. Again, 9/11 calls are considered to be True Threats, so they must be treated as if the emergency is happening thus giving valid cause for warrantless entry. So long as it is in plane site or a plausible hiding spot for the initial incident, it's fair to use. (I.e. if you find drugs in a sugar bowl on a hostage situation, it would be ruled out because who honestly thinks the hostage might be inside a sugar bowl).
    – hszmv
    Jan 24, 2019 at 19:12
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    There is a quite elaborate jurisprudence regarding when information from anonymous informants constitutes probable cause, and the mere fact that the anonymous informant did so via a 911 call does not, per se, suffice to establish probable cause. Given the general loosening of probable cause standards, however, in recent jurisprudence, the plain sight discoveries of evidence made while serving a warrant issued based upon information that was false but believed to provide probable cause would probably not be suppressed in a criminal case.
    – ohwilleke
    Jan 29, 2019 at 18:18
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    @ohwilleke: I can't believe I missed this point, but it's basically SWATTING someone to give law enforcement cause to enter someone's property and find plain sight evidence of an actual crime.
    – hszmv
    Jan 29, 2019 at 18:33
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    @hszmv It most definitely is SWATTING and it very likely constitutes both criminal and tortious conduct by the person providing the false information, but that fact isn't controlling in a case where police get a warrant based on anonymous evidence that they do not know to be false that has indica of credibility of some kind.
    – ohwilleke
    Jan 29, 2019 at 18:37
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    @ohwilleke: The situation would more likely provide a warrant exception in the form of exigent circumstances OR Safety Check as it is called into 911 as a crime in progress in which the life of an individual is in jeopardy. The cops wouldn't wait around for a warrant to clear before they try to get control of the situation. At this point they are making a good faith lawful entry.
    – hszmv
    Jan 29, 2019 at 18:48

I used to be a litigator in civil rights cases against the police for misconduct against civilians: that personal experience is the basis for my discussion herein. I practiced for 11 years before quitting the profession.

The Fourth Amendment search and seizure protection is basically dead except for white collar crime and entry into the home. Your situation involves one of the areas where the 4th Amendment still imposes some limitations on police action. Such protection is always incomplete and contingent. If the police really want to enter a home they can and will do so, and they can and sometimes will use deadly force to overcome resistence. The fourth amendment does not barricade doors or make someone bulletproof.

Police generally are not held accountable for violations of civilian rights, in the absence of substantial and sustained political pressure. You cannot sue and win money damages for the mere violation of a civil right; you must show that the violation caused economic, physical or mental harm that can be proven, and are quantifiable and compensable without getting too theoretical. In federal courts police have near-total immunity to suit because of a judge-made loophole in the civil rights law called qualified immunity. That rule states that police are immune to suit unless they violated a clearly established consitutional right and "no reasonable police officer" in the officer's circumstanmces would have thought the officer's conduct was lawful. JUdges decide these issues, not juries, and they can do so at any stage in the case if they base their decision on facts that are not in dispute. Courts love doing this. The constitutional right is not defined at a general level ("right to be free from warrantless entry"), but with highly specific reference to the facts of the case. Almost all constitutional law is left unsettled and ambiguous by the judiciary even at the general level; it is very difficult to make the case that a particular fact pattern gives rise to "clearly established" rights. What a reasonable police officer is, or whether any such officers exist, has never been defined. This hypothetical officer is basically a vessel to be filled with judicial bias (both individual and institutional). Courts usually have little interest in evidence of best practices or police department policy: the cases say that an officer can violate policy, procedure, etc. and still pass the reasonable officer test.

Qualified immunity kills most claims against individual officers. A case called Monnell kills most cases against the municipality or police department. That case says that you cannot sue the agency or city just because they employ an officer that committed a tort against you. You Have to show that the violation of your rights was the result of police following an unconstitutional policy or widespread and officially-tolerated practice. Police departments therefore do not create official policies or shield rulebooks from disclosure as classified. And the courts will throw out nearly anything you bring as evidence of a policy and practice short of videotaped confession by the mayor. On the criminal side, they police have surprisingly little interest in what happens in criminal cases that arise out of their arrests and investigations. Police officers are rewarded or punished internally based on whether they meet (illegal) quotas on writing tickets and making arrests. Whether charges are filed or not by the DA, and anything after that, has no effect on them in their jobs. If a judge finds out that a cop committed misconduct or perjury, the judge will do nothing. (This immunity from consequences prevails, unless there is substantial and sustained political pressure, of a kind that is rare enough that police can safely ignore the possibility in their day-to-day work). SO, when you ask the question: "Can the police do x y or z," the answer is generally yes, whatever you are referring to. They can do whatever they want because there really aren't any powers that oppose them or any systems in place to limit their conduct. Civil unrest is really the only thing that limits police conduct.

Take note that neither the probable cause test nor the qualified iummunity test give any consideration to what the police actually believe or what they want to accomplish. Whether there is probable cause is determined by what a reasonable police officer would conclude based on the facts objectively available. Police may have bad or racist or even illegal motives in taking action -- the courts do not want to know about it and will not entertain arguments of that kind, as a general rule. Generally, facts act as a one-way ratchet: a fact that is not obviously absurd or baseless is usually considered something on which a "reasonable police officer" can rely. The existence of other facts negating probable cause usually makes no difference unless they are either totally overwhelming or totally indisputable (video of an event is not indisputable). There is no duty to investigate to determine the true facts before taking action. There is no legally-enforceable duty to perform any police functions, including protecting citizens from crime. Thus, doing nothing is a VERY low risk move for police except under very unusual circumstances. The police will freely invent facts to support their official conduct: perjury is a fundamental tool of modern policing, as indispensible as the radio and the gun. To repeat, judges and district attorneys who learn that a cop has committed perjury will do nothing. I would have no fear betting my life that a police officer could commit perjury 100 times without being punished once.

So, unless you are specifically addressing the question of the admissibility of evidence obtained in an entry/search in a criminal matter your question really should not be: "Is there probable cause?" it should be: "Do the police want there to be probable cause?" If the answer to the second question is yes, then the police will almost certainly enter.

Generally, the police are interested in maximizing their overtime hours while doing as little real work as possible. Something that doesn't lead to extra overtime pay, doesn't get them points towards their quota, and which involves effort of any kind, is going to be a very low priority for the average cop. This includes stopping a crime in progress. However, some police have emotional investment in being in control of their territory. Something they see as a threat to that control will meet their vigorous and often physical opposition, even if the thing threatening their control is perfectly legal. In addition, police can be stirred to action by reputational concerns. WHile having a bad reputation (individually or collectively) poses no real threat to them, most police have some concern for their reputation to the extent that it may affect their social status. In high-visibility situations, police may either change their conduct to be more in line with public expectations, or take steps to conceeal their conduct or confuse onlookers.

So, just because a violent crime is alleged to be in progress, does not mean the police will want to do anything about it. Will it bring overtime? WIll handling it be easy? If its a violenmt crime, yes to the first question and no to the second. It could go either way. If the victim is a disfavored minority, this is less liklely to trigger a territorial defense response than if the victim is someone the officers see as within their sphere of protection. Police repsonse to domestic violence crimes is extremely variable, but disinterest often wins out because they are difficult and dangerous to handle, and the police see them as a problem which police action usually can't solve (and this is not without reason).

Most police forces have task forces of various kinds (swat, drug task forces) which get special training, and more importantly, higher status and cool militaristic equipment. Many of the officers on these task forces enjoy the excitement of kicking down doors, etc., and they will take action in a wider variety of situations, even if the factors that motivate most police officers are absent. So the same scenario can go very differently depending on whether it is regular uniforms or task force guys who show up first.

So, whether the police will want probable cause to exist will depend on whether the incident presents motivations or disincentives of the kinds mentioned above, and it will depend in part on who the police are who are available to respond.

Just so you have it clear, the 4th Amendment rule on entry to the home is this: If the police have a warrant they can enter according to its terms, without no need for any additional facts or circumstances to be present. If they don't then they need BOTH probable cause and exigent circumstances. Exigent circumstances means some kind of an emergency. It isn't only the sort of emergency where people might come to harm: the imminent destruction of evidence can also be an exigent circumstance. Again, police who want to enter will help themselves by inventing additional facts to meet the standards. Police who don't want to take action are perfectly capable of ignoring a truckload of exigent circumstances. Police are also good at using lies (which is legal) and threats (sometimes legal, sometimes not) to induce the person to allow them to enter, at which point civil rights are no longer an issue. Because the cop's level of motivation is a major factor in determining what happens, there is often inconsistency in how similar incidents are handled at different times by different officers.

The thing that the forth amendment protects is not your right not to have cops barge into your home, it is your right not to have the government build a case against you through fishing expeditions inside your home. Whatever the Constitution may say, the only real recourse the householder has is, in their criminal trial, to demand and possibly obtain exclusion of the evidence obtained in violation of their rights. It can take years to win a concession that your rights were violated. Many people spend those years in prison. The court may also agree that your rights were violated but allow the evidence anyway, for a variety of reasons, most of them disgraceful.

JUst to wrap things up, state and local officers are subject to the limits of the consitituion, at least theoretically, and criminal proceedings must, in most aspects, meet federal constitutional standards. These standards are low. State/local officers and state courts are also bound by their state constitutions. All states have rights analogous to the bill of rights written into their constitutions. Most leave it at that, and most state judiciaries take an active interest in making sure their constitutional law is basically the same as the federal. However, there can be differences, and if there are differences, they have to be in favor of the defendant. On the civil side, most states have rules similar to qualified immunity and Monell, making it very hard to sue police. Some, in addition, have limitations on damages which make even "successful" cases hardly worth the trouble. That said, a warrantless entry is a fact pattern where some legal protections still exist, where there is a non-hypothetical (small but greater than zero) possibility of success in a civil suit or a motion to exclude criminal evidence. It is one of the few fact patterns that can get even conservative judges angry at the police/municipality (occasionally).

In your proposed plot, I would expect that the police would have trouble determining in real time which calls were illegitimate. The doors they kick down usually belong to people with no social status, and police calibrate their conduct accordingly. Thus, the police could find themselves in unfamiliar and uncomfortable circumstances if they were uncertain whom or what they might find at a 911 address. Most would probably err on the side of caution, and this could result in them neglecting a real emergency. With asympathetic non-minority victim, such a scenario could generate enough political pressure to get their attention, if not to threaten their security. I think they would pretty quickly tire of the extra work, reputational risk, and interference with their territorial control, and would make stopping the crank caller a high priority. Police departments do not know how to investigate crime, which would be a problem for them, but manpower can substitute up to a point for institutional failure to prioritize investigative capabilities. Some task forces have officers of skill and training (often military training), and it would probably also be possible to get the feds involved in a case like that, if they were so inclined.

I hope this helps.


So I make a 911 call claiming there is a crime in progress at address X. If the police believes that this is fake, but they are either legally required to visit X even if they are sure it is fake, or they believe it is fake, but are not sufficiently sure to take the risk of not going, in these two cases they can go to X. And then whatever they see in open view is fair game.

On the other hand, if the police believes my call is fake, but they just see it as a good opportunity to have a look at X, then they wouldn't be entering lawfully.

In both cases, if a person living at X goes to court because of what the police found, then they would try to convince a jury that the visit was unlawful. Depending on the exact situation, the jury, and the quality of the lawyers involved, they might succeed or fail.

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