What if police find a dead body during an illegal search? Suppose police conduct an illegal search of a residence (no warrant, no consent, no probable cause) and find a dead body. There is plenty of evidence in plain sight that it was a murder and also evidence of who the killer is: he is standing next to the body with the murder weapon in his hand. The murderer, being a smart lawyer, keeps his mouth shut. Would all of the evidence found during the search be excluded under the "fruit of the poisonous tree" doctrine? If so, how could the murderer be prosecuted?
If that which you describe in your comment ( Facebook post as only basis for warrantless search) is, and can be shown, to be the only basis for the search, and there was no evidence of a crime in plain view when they arrived.....then yes, it is likely the search and all evidence acquired from the search would be excludable. As to whether the individual could still be prosecuted, that depends if a case could be built independent of the evidence collected during the search.
Criminal charges are filed and prosecuted by the government, on behalf of the public, and there is no requirement for approval or cooperation by the victim. As a policy matter, a DA may decide to not charge a person in case the victim is unwilling (though less so in cases of domestic violence), perhaps because of the widespread impression that the victim has to "press charges" (which indeed they would have to do in the case of private prosecution, which is no longer allowed in the US). The alleged victim's reddit exchanges on the topic are here. An uncooperative victim does not make a good witness, even if they are compelled to testify. The police statement that they cannot pursue an investigation should not be interpreted as a statement of law, it's probably a statement of policy and practicality.
There is a lot of confusion over the difference between reasonable suspicion and probable cause. They are not the same thing. Reasonable suspicion is any justifiable belief that a crime has been or is about to be committed. Probable cause requires an officer to have actual, tangible evidence that you have committed a crime. Only after probable cause has been established can an officer arrest you (with limited ability to search your immediate person and effects). Reasonable suspicion only requires some articulatable justification that you did something wrong. The police can detain you on reasonable suspicion, and they do not have to tell you why. This is called a Terry stop (after Terry v. Ohio where the Supreme Court ruled this was legal). However, they can only detain you long enough to ascertain whether or not they have probable cause to arrest you. If after conducting a preliminary investigation they can't find probable cause to make an arrest, they have to let you go. In that video, we have a guy walking around in Texas with a shotgun and some shells. We never see what this guy looks like or how he's carrying himself, but he appears to be a troll. The cops received a call, so they investigated. They had all the reasonable suspicion they needed to detain him. Texas is an open carry state (a person can walk around openly with a gun), and it is not a stop-and-identify state (the police cannot demand that you ID yourself). Therefore the man did not break any laws. But neither did the police officers. They were doing their job by asking questions, and after failing to find any evidence, they let him go. If he had run before the officers had cleared him to leave, they could have chased him down and arrested him. That is, after all, what a detention is. You don't get to run away because you don't recognize a cop's authority to stop you. And fleeing a law enforcement officer is a crime. But you do have the right not to answer any questions, including (in some states) what your name is.
In the United States who has the authority and what is the procedure to determine if conduct by an individual is "illegal"? You are conflating several different ideas here, which is probably the source of your persistent confusion. 1) Actions are legal or not Illegal: Not authorized by law; Illicit ; unlawful; contrary to law The law sets out certain things that you must do (you must stop at a red light) and things you must not do (you must not drive under the influence). Sometimes actions fall into a gray area of the law, or aren't addressed at all, but if something is spelled out, then it's very clear whether the abstract action is legal or not. Running a red light is illegal. Driving under the influence is illegal. There are definitions and specified penalties for both. 2) A person may or may not be guilty of an illegal action Guilty: Having committed a crime or tort Abstract actions can be legal or illegal, but people commit crimes. When someone commits a crime, they are guilty of that crime. This is true whether or not they are ever prosecuted, or even if law enforcement knows who the guilty one is. If someone runs a red light at 2 in the morning on an empty street, it's still illegal and thus they are guilty of running a red - but no one will ever catch them. If someone is shot in the middle of the street, then someone is guilty of shooting them. Again, the shooter may never be found, but whoever they are, they are still guilty. 3) An individual may or may not be guilty of the crime of which they are charged. Charge: the statement of the alleged offense that brings a person to court If law enforcement (whether your local traffic cop or the FBI) believes that you are guilty of a crime, they can charge you with committing it. They may be right. They may be wrong. But the suspicion of having committed it is enough to charge you. To continue the traffic example: If an officer sees you running the red light, they can write you a ticket (effectively charging you) for doing so. They may or may not actually be right (it could have been yellow or malfunctioning, for example), but law enforcement has the power to charge regardless. 4) A defendant may or may be found guilty and convicted. Conviction: In a general sense, the result of a criminal trial which ends in a judgment or sentence that the prisoner is guilty as charged. Finding a person guilty by verdict of a jury. This is where the presumption of innocence comes in - the default assumption is that the accused did not commit the crime that they are being charged with, and it's the prosecutor's job to prove otherwise. If the accused is found to not be guilty of the crime, then they (presumably) didn't do it - it doesn't necessarily mean the crime didn't happen, just that this specific person didn't commit it. Alternatively, the defendant can be found not guilty for other reasons - the judge or jury can determine that the crime didn't take place, took place but was justified, or the defendant wasn't in their right mind at the time. On the other hand, if they are found guilty, they're convicted and sentenced to whatever an appropriate punishment is. TL;DR Whether something is legal is determined by the legislature when they pass laws. Someone who commits an illegal act is guilty of doing so, even if they are never charged. Again, this is determined by the legislature when they pass laws. People are charged with violations of specific laws by law enforcement. Defendants can be found guilty by the court system. In other words, only the courts can determine whether a specific individual actually committed illegal behavior, but the behavior is still illegal regardless.
The police officers themselves are covered by Qualified Immunity - to put it briefly, a government official acting in their official capacity in a discretionary act (as in, they have some discretion in whether/how they carry out the act) is immune from suit so long as they pay reasonable deference to relevant law. In the case of the police, so long as the search or seizure itself is reasonable (either because there is a warrant, or because they had probable cause), they can take appropriately destructive measures to carry out their duty. Even if the search or seizure is later found to have been unreasonable, an officer may still have Qualified Immunity unless their action violated "clearly established statutory or constitutional rights of which reasonable person would have known" (Harlow v. Fitzgerald). However, a search/seizure doesn't give the police license for arbitrary destruction, whatever they do has to be reasonably pursuant to the legal search/seizure. For example, if a suspect is barricaded in a house with a gun, they can knock down doors, windows and walls to apprehend them. On the other hand, that does not mean the officers can then break open safes to try and find evidence - once their probable cause for the entry is fulfilled (apprehending the suspect), they need to get a warrant to do more than a plain sight search of the house. Warrants will specify what items are being searched for, so even with a warrant the police have to take reasonable measures to carry it out - an example of an unreasonable measure would be to tear into walls in order to try and find a stolen bicycle. On the other hand, tearing into walls could be justified if their warrant included searching for drugs from a dealer, where it is not uncommon to hide them in the walls. States and the Federal Government enjoy Sovereign Immunity from suits in most cases. There are some exceptions, but none would apply in this case so long as the general policy of the police department was not illegal or unconstitutional. However, county and city governments do not enjoy Sovereign Immunity and state governments and the Federal Government often allow suits against them for negligence from their actors, so someone injured by unreasonable police action can usually try to recover damages from the officer's department.
It depends on the nature of the crime, among other things. Under Section 8 of the Police and Criminal Evidence Act 1984 (PACE) the police must provide evidence to a court that a search warrant is necessary to secure and obtain evidence relevant to an ongoing investigation into a crime. If there is evidence that time is of the essence with regards to the evidence at stake (e.g. there is a high probability that the evidence will be destroyed unless it is secured immediately) then the search warrant will be expedited. Once the search warrant has been secured, it will be an operational matter for the police to decide when and how to act on it. They could choose to do a dawn raid, for example, or they could monitor the suspect for a week and then search the property when the suspect is out. Be aware that under Section 18 of PACE, a search warrant is not necessarily required. The police may, in the course of arresting someone for an indictable offence, search the premises without a warrant provided certain criteria are met. Of course, this is predicated on the police having grounds for arrest, and in the vast majority of cases, a search warrant will be obtained.
The question is oddly phrased: The law does not give allowances for its violation. Many laws have exceptions. E.g., the law against killing endangered animals contains an exception for defensive killings. Perhaps you are thinking of safe harbors? For example, there are general provisions in the law like "exigent circumstances" that allow police to proceed with actions that, absent those provisions, would constitute violations of law. "Permission" to violate a right can be granted explicitly in the form of a warrant, which allows law enforcement to "violate" specific property and freedom rights. Finally, one might consider an executive pardon or jury-nullification to be ex post "permission to break the law."
It isn't clear that the example you give is illegal police action, but let's assume that it is for the sake of this question, since it doesn't affect the analysis. If possession is not compelled, then it is voluntary.