Unreasonable search and seizure refers to an unjustified or improper examination conducted by a legal official in which items are identified and/or taken. In the vast majority of countries, the police or other law enforcement officials cannot simply search someone for no reason. If these officials do not follow the proper legal steps and conduct a search, that search can be classified as unreasonable; if things are taken during the search, the seizure can also be classified as unreasonable.
Within the United States, those who are suspects in a crime are vested with certain rights in the US Constitution. The Fourth Amendment in particular protects against unreasonable search and seizure. Various other countries also guarantee protections in their governing doctrines, such as the Canadian Charter or the English Bill of Rights.
Within most countries and jurisdictions, police or legal officials must follow one of several protocols before conducting a search without permission. First, the police officials can obtain a warrant after demonstrating probable cause. Probable cause means there is evidence to suggest that a search will turn up further evidence of a crime or other wrongdoing.
If the police do not have a warrant, usually search is prohibited. In some cases, however, exigent circumstances can be sufficient to permit a search without a warrant. Exigent circumstances refer to situations in which someone may be in danger if the police do not search immediately, such as if the police hear screams behind a locked door.
The protections against unreasonable search and seizure apply to the search of a person and the search of property. For example, police may not pat someone down or force him to empty his pockets without justification. Furthermore, police cannot enter someone's property or search a person's car without a warrant or reasonable justification or suspicion for the search.
If proper protocol is not followed and an unreasonable search and seizure does take place, any evidence obtained from that illegal search generally cannot be used against the person. For it to be used, law enforcement officials must convince a judge that the evidence would have been found, even without the unreasonable search and seizure. Furthermore, if evidence found in an illegal search turns up other evidence, that other evidence cannot be used because it is considered "fruit of the poisonous tree" since it would not have been found but for the violation of the rights of the accused.