Co. v. United States, All evidence developed and obtained based on evidence obtained unconstitutionally is "fruit of the poisonous tree" and cannot be used at trial. Mapp v. Ohio, Exclusionary rule applied to state prosecutions. Schmerber v. California, The application of the Fourth Amendment's protection against warrantless searches and the Fifth Amendment privilege against self incrimination to searches that intrude into the human body means that police may not conduct warrantless blood testing on suspects absent an emergency that justifies acting without a warrant. Katz v. United States, The Fourth Amendment's ban on unreasonable searches and seizures applies to all places where an individual has a "reasonable expectation of privacy." Terry v. Ohio, Police may stop a person if they have a reasonable suspicion that the person has committed or is about to commit a crime and frisk the suspect for weapons if they have a reasonable suspicion that the suspect is armed and dangerous without violating the Fourth Amendment. Mancusi v. DeForte, The privacy rights defined in Katz extend to the workplace. Bivens v. Six Unknown Named Agents, Individuals may sue federal government officials who have violated their Fourth Amendment rights even though such a suit is not authorized by law. The existence of a remedy for the violation is implied from the importance of the right that is violated. United States v. United States District Court for the Eastern District of Michigan, Government officials must obtain a warrant before beginning electronic surveillance even if domestic security issues are involved. The "inherent vagueness of the domestic security concept" and the potential for abusing it to quell political dissent make the Fourth Amendment's protections especially important when the government spies on its own citizens. Illinois v. Gates, The totality of the circumstances, rather than a rigid test, must be used in finding probable cause under the Fourth Amendment. New Jersey v. T. L. O., The Fourth Amendment's ban on unreasonable searches applies to those conducted by public school officials as well as those conducted by law enforcement personnel, but public school officials can use the less strict standard of reasonable suspicion instead of probable cause. O'Connor v. Ortega, In the absence of reasonable workplace policy to the contrary, the Fourth Amendment applies to searches of public employees, their belongings or workplaces by their superiors if done with reasonable suspicion for administrative reasons. Vernonia School District 47J v. Acton, Schools may