Under the Fourth Amendment, a search occurs when government action obtains information either by committing a trespass (from Jones) or in violation of the reasonable expectation of privacy of the one being searched (from Katz).
- The person searched must have exhibited an actual subjective expectation of privacy.
- Society must be prepared to recognize that this expectation is objectively reasonable.
The open field doctrine, as laid out in Oliver, states that searching an open field is not a search within the meaning of the Fourth Amendment because, even though it would be a trespass at common law, there is no reasonable expectation of privacy in an open field.
The curtilage of a home is the land immediately surrounding it.
- The distance of the area from the home
- Whether the area is within an enclosure surrounding the home (I.e., if it's in a fence)
- The nature of the use to which the area is put
- Steps taken to protect the area from observation
The basic analysis behind this is whether the land is so intimately tied to the home that it should be placed under the home's Fourth Amendment protection.
Aerial searches are not searches under the meaning of the Fourth Amendment to the Constitution of the United States as long as the police are in a lawful airspace because there is no reasonable expectation of privacy from being viewed from such places since anyone can fly a plane there.
Sense-enhancing technology constitutes a search under the Fourth Amendment if the technology is not generally available to the public and it reveals information that one would reasonably expect to be private.
According to Kyllo v. United States, taking a picture of the infrared light being emitted from someone's home is considered a search under the Fourth Amendment because it can reveal the heat being generated in various rooms of the house, which can reveal details about the interior of the home, which has the greatest expectation of privacy, and because when Kyllo v. United States was decided, infrared cameras were much more expensive than they are today.
Vehicles have lower expectations of privacy because they are made to transport one through the public and because they have windows allowing anyone to see inside.
There is no reasonable expectation of privacy in the phone numbers one dials, only in the contents of such calls.
Dogs can be used to search during a lawful traffic stop without it constituting a search under the Fourth Amendment to the Constitution of the United States because there is no reasonable expectation of privacy in the smells that one gives off.
Dogs being used within the curtilage of one's home is a search however because, even if though people generally have a license to enter premises for certain purposes like going up to the front door, bringing dogs to sniff is exceeding the police's license to enter and is therefore a trespass.
For a Fourth Amendment search to be constitutionally permissible, it must be reasonable. This generally means that it must be conducted pursuant to a valid search warrant based upon probable cause. Warrantless searches are per se unreasonable.
Brinegar v. United States
Probable cause exists where "the facts and circumstances within their [the officers'] knowledge and of which they had reasonably trustworthy information [are] sufficient in themselves to warrant a man of reasonable caution in the belief that" an offense has been or is being committed.
An officer's subjective intent or belief is irrelevant in determining probable cause. Only what a reasonable officer would believe matters.
A mistake of fact or law is okay as long as it is reasonable for an officer to make.
Probable cause requires more than just reasonable suspicion, but it does not require evidence that would justify a conviction.
Anonymous tips alone cannot establish probable cause, but they can when combined with the totality of the circumstances. Especially important in such determinations are whether the informant is credible—likely to be telling the truth—and reliable—likely to have knowledge. Thus, the veracity of the informant and his basis of knowledge should be analyzed.
Note that just because an anonymous tip turned out to be true does not mean that it was credible. The totality of the circumstances must establish probable cause before conducting the search, not after. This can be done by corroborating parts of a tip that do not require infringing upon one's reasonable expectation of privacy.
- A warrant must relate to a specific crime.
Executing a Warrant
Officers can detain and question people in the immediate vicinity while executing a warrant for the purpose of ensuring the safety officers and others.
Generally, officers must knock and announce their presence when entering a home while executing a warrant. However, courts apply a reasonableness test to this requirement which allows exceptions for several reasons where knocking and announcing would cause more harm than good:
- Exigent circumstances
- Officer safety
- Preventing the destruction of evidence
Exceptions to the Warrant Requirement
Searches made in hot pursuit of a suspected felon are valid when speed is essential for the safety of officers or others. The hot pursuit exception does not permit police to enter a home without a warrant for a routine arrest however, even if they have probable cause that one committed a felony.
Police may enter a home without a warrant when they have an objectively reasonable basis for believing that an occupant is seriously injured or immediately threatened with serious injury.
Destruction of Evidence
Warrantless entry of a home to prevent the destruction of evidence is reasonable under the Fourth Amendment—and thus allowed—when the police's conduct was reasonable.
The police's conduct is reasonable when the police did not create the exigency by engaging in or threatening to engage in conduct that violates the Fourth Amendment.
Drivers may be required to submit to a breathalyzer test without a search warrant to prevent the destruction of evidence but not a blood test because that would be too intrusive.
For the plain view exception to apply, it must be immediately apparent that the item is illegal from a location where the officer is lawfully located.
Although it is called the "plain view" doctrine, an officer may seize evidence he detects with any of his senses. Most notably, it permits the seizure of evidence felt during a stop-and-frisk that is immediately determined to be illegal.
One of the most important exceptions to the warrant requirement is the automobile exception, permitting officers to search anywhere inside a movable vehicle (even if it is not immediately mobile) without a warrant as long as there is probable cause to believe that that area of the vehicle could contain evidence of a crime.
This is justified because vehicles have lower expectations of privacy because they are made to transport one through the public and because they are subject to many regulations.
The automobile exception applies not only to the passenger compartment. It also permits searches of the trunk or containers inside a vehicle provided that the police have probable cause that contraband is contained therein.
- If a container that police have probable cause to search is put into a vehicle, police then have probable cause to search both the vehicle and the container.
- This includes passengers' items if police have probable cause for them too, such as by virtue of them being in the area of control of a suspect.
A warrantless search without consent conducted when a lawful arrest is made is reasonable within the area of the arrested person's immediate control. This is true regardless of the crime arrested for, but the person must actually be arrested.
The purposes of this exception are officer safety and the preservation of evidence.
Police cannot search a cell phone incident to arrest.
Police have the right to search the passenger compartment of a vehicle incident to the arrest of an occupant of the vehicle if he has access to it or if the police reasonably believe that the vehicle contains evidence of the crime arrested for.
Routine inventories subject to standard police procedure are reasonable under the Fourth Amendment.
Inventory searches are permitted for the purposes of:
- Protecting the confiscated property
- Protecting the police from liability
- Protecting the police from dangerous items
Inventory searches must be conducted for these purposes to be valid under the Fourth Amendment. They cannot just be to look for evidence of a crime.
Voluntariness is assessed under the totality of the circumstances. Police cannot coerce a suspect to give consent; it must be an intentional relinquishment or abandonment. It is not necessary to prove that the suspect knew of his ability to refuse to consent.
Consent can be withdrawn at any time.
Other people at a residence can give consent to a search as long as police reasonably believe that the person has authority to give consent for the location. However, if any resident expresses a refusal, this trumps any consent given. However, police can come back after a non-consenting resident leaves and get valid consent to search from the consenting resident.
Special need searches are searches with an immediate objective of a special need separate from tradition law enforcement purposes. They are thus permitted without a warrant or probable cause as long as the government interest outweighs the individual's privacy interest. (This is a two-part test.) In weighing an individual's privacy interest, both the character of the intrusion and the nature of the intrusion must be considered.
Generally, routine administrative searches require either a warrant, consent, or another exception to the warrant requirement. Absent such requirements, administrative searches must give an opportunity for precompliance review before a neutral decisionmaker unless it is a closely regulated business.
In applying for a warrant, for an administrative search, probable cause exists if reasonable legislative or administrative standards for conducting such inspection are satisfied for the dwelling. Such standards are reasonable if they are based on the passage of time, the nature of the building, or the condition of the area.
- There must be a substantial government interest that informs the regulatory scheme pursuant to which the inspection is made.
- The warrantless inspections must be necessary to further [the] regulatory scheme.
- The statute's inspection, in terms of the certainty and regularity of its application, must provide a constitutionally adequate substitute for a warrant.
- It must:
- Advise the property owner that the search is being made pursuant to the inspecting officers and has a properly defined scope
- Limit officer discretion
- It must:
The Supreme Court has recognized four industries as being closely regulated:
- Liquor sales
- Firearms dealing
- Running an automobile junkyard
The government has authority under the Fourth Amendment to conduct suspicionless searches at the border, including removing the gas tank from a car, based on its interest in protecting the border.
This also allows mail entering the country to be inspected without a warrant, as long as there is reasonable cause to suspect that there is something illegal therein.
While a Fourth Amendment seizure occurs when a vehicle is stopped at a checkpoint, there is no Fourth Amendment violation for sobriety checkpoints or checkpoints based on exigency (catching a dangerous criminal) because the main objective is public safety, not general crime control.
The government's interest in the checkpoint must be balanced against its invasion on the motorist.
Searches in schools only need reasonable suspicion of evidence of violating the law or a rule of the school.
Measures used in such searches must be "reasonable related to the objectives of the search and not excessively intrusive in light of the age and sex of the student and the nature of the infraction."
Neither a warrant nor probable cause is needed for a search of a government employee's workplace and work phone as long as it is motivated by a "legitimate work-related purpose" and it is not "excessively intrusive".
Strip searches of people entering jail are permissible as long as they are reasonably related to legitimate "penalogical interests".
DNA may be collected from people validly arrested as part of a routine booking procedure and used to investigate.