The fourth amendment makes no explicit provision for warrantless searches. The first clause of the amendment provides simply that "the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated." This general prohibition is followed by another clause that provides more particularly for the issuance of search warrants. The amendment itself does not indicate what connection there is between the two clauses (which are separated only by a comma and the word "and"). Accordingly, its application to various kinds of warrantless searches has depended heavily on which clause the Supreme Court favors. On the one hand, the first clause might be regarded as the main provision, searches pursuant to a warrant being only one type of reasonable search that is authorized. Or, if the second clause be emphasized, the absence of a search warrant might be regarded ordinarily as itself making a search unreasonable, the requirement of a warrant being disregarded only in exceptional circumstances including particularly lack of an opportunity to obtain one.
Some kinds of warrantless search are obviously necessary to the performance of other official duties. A police officer who unexpectedly makes an arrest of someone committing a violent crime may necessarily search him for weapons. If the Fourth Amendment were deemed to prohibit every search without a warrant, one would be driven to the conclusion that the arresting officer's conduct was not a search at all within its contemplation. Current interpretation of the Fourth Amendment has avoided such an all-or-nothing approach. The amendment is applicable to a very wide range of official conduct interfering with expectations of privacy; within that context, the prevailing rules have established a number of situations in which a warrant to search is unnecessary.
The first such situation is the search incident to an arrest. The need for an arresting officer to ensure that the person whom he arrests does not have in his possession a weapon or means of escape is the basis for the most frequently applied exception to the requirement of a warrant. Because police actively engaged in crime prevention often come on circumstances calling for an arrest without advance notice, a search incident to the arrest must be made without a warrant. Although not strictly necessary to effectuate the arrest, another reason for allowing a search is to prevent the arrestee from destroying evidence in his possession. The Supreme Court said in chimel v. california (1969) that all three justifications are sufficient to authorize a search of the arrestee's person and the area "within his immediate control" from which he might grab something. That general rule defines an area that may be searched without a warrant following an arrest, whether or not there is particular reason to believe that anything subject to seizure is there to be grabbed and, indeed, whether or not there is reason to believe that the arrestee is likely to grab anything. In effect, the rule authorizes a not-too-intensive search of the arrestee, including small containers on his person like a wallet or purse, and a small area around the place of the arrest. If a person were arrested in his home, the rule would authorize a limited search of the table or desk at which he sat, but not all the contents of the room or the contents of other rooms.
The scope of this rule illustrates a general feature of the exceptions to the warrant requirement. Although from time to time the Court has intimated that such exceptions depend on an emergency that demands a search before a warrant could practicably be obtained, the rule does not depend on a particularized finding of that kind. In some cases, the rule has been applied to uphold a search even though the arresting officers could easily have (or even had) removed the person from the area searched or immobilized him. (One might note also that the rule applies fully to arrests that are not unanticipated, even though in that case a warrant could presumably have been obtained.) The evident rationale is that a warrantless search incident to an arrest is so often necessary that it is impractical to require particular justification in each case.
Warrants are not required for automobile searches in various circumstances. Although automobiles (and other motor vehicles) as private places enjoy the protection of the Fourth Amendment, two distinct lines of analysis have markedly limited the application to them of the requirement of a search warrant. Automobiles, the Supreme Court has said, are subject to much greater regulation and inspection than dwellings; the expectation of privacy in them is much less. Having reached that judgment, the Court has not modified it to differentiate between areas like the back seat that are generally open to view and closed or concealed areas like the trunk or glove compartment that are not.
If police officers obtain lawful custody of an automobile which they have probable cause to search for evidence of a crime, a warrantless search is allowed for some period, a few hours at least, after custody is obtained. This rule is based not only on the lesser expectation of privacy attached to an automobile but also on its mobility and the unpredictability with which custody often is obtained. The Supreme Court has not been persuaded that the immobilization of the car while it is in custody ordinarily makes it unnecessary to allow a search until a warrant has been obtained. Second, if officers have lawful custody of an automobile and routinely follow a regular custodial procedure, like an inventory of its contents, a search performed as part of the procedure is permitted. The routine nature of such practices, which are followed by many police departments, has persuaded the Supreme Court that they are reasonable. (Also, the arrest-incident exception authorizes a thorough search of the passenger compartment of an automobile, including all containers within it, as an incident of the arrest of an occupant.)
A search at the time and place of an arrest is likely to be limited by the circumstances to weapons or means of escape and only the most obvious evidentiary items. Later, when the person is about to be placed in detention or while he is in detention, there is opportunity for a more thorough search; sometimes, the evidentiary significance of an item is not plain at the time of the arrest and is revealed as the investigation proceeds. The police have authority to make a very thorough search without a warrant of items removed from the arrested person and held by them while he is lawfully detained temporarily in a jail or similar facility. The arrest, it has been said, being the more significant interference with liberty, includes the lesser intrusion on privacy occasioned by the search. Furthermore, a search is authorized at the time and place of the arrest and it is routine administrative procedure to impound and perhaps inventory a person's effects before he is placed in a cell; therefore, it is reasoned, the fact that some time elapses between the arrest and the search has no constitutional significance.
The most general exception to the requirement of a search warrant allows the police and other public officials to search without a warrant in exigent circumstances :an emergency furnishing adequate grounds for a search that has to be carried out before a warrant can be obtained. A search incident to the unanticipated arrest of a potentially dangerous person is an example of this more general category, although justified by a special rule. Another example is an entry and search of private premises while in "hot pursuit" of someone who has just committed a crime; police officers are not required to interrupt the chase until they have obtained a warrant. Similarly, officers responding to a cry for help or acting to avert a danger inside private premises need not wait to obtain a warrant. It has usually been held also that if officers have particular, reliable information that specific evidence of crime is about to be destroyed and there is not time to obtain a warrant, they can enter to prevent its destruction.
In such cases, authority to search without a warrant is tailored to the emergency. The officers claiming the authority must not themselves be responsible for the existence of the emergency; if, for example, they unreasonably delayed applying for a warrant until it was too late, they could not then assert their inability to obtain a warrant. Also, the authority extends only as far as the emergency requires. Entering in hot pursuit, officers could also search for weapons that the person whom they are pursuing might use against them; but once having him in custody, they could not continue to search solely for evidence.
The regulation of persons and goods entering or leaving the country has always been understood to provide a special basis for warrantless searches. Public officials who supervise traffic across the border are authorized to inspect goods and to require a person crossing the border to submit to a thorough search. (See border searches.) Some comprehensive statutory programs for the regulation of industry and commerce have authorized warrantless entries and inspections. Such procedures have been upheld if a requirement of a warrant might be expected to frustrate the regulatory program and the business in question is generally subject to close governmental supervision: for example, gun and liquor dealerships, and mines. Similarly, the Supreme Court has held that inspection visits to the home by a welfare official can be made a condition of receipt of public welfare. In other cases, the Court has concluded that the regulatory purpose of a statute did not require that warrantless (unannounced) searches be allowed.
In some circumstances, a brief invasion of personal privacy less intrusive than a full search is allowed without a warrant. Most common is the protective "frisk" or pat-down of a person whose conduct a police officer has reason to investigate and who he reasonably suspects may be armed. There being no opportunity to obtain a warrant, the safe performance of the officer's investigative duty justifies a limited search for weapons. Likewise, traffic officers are allowed to make routine checks for driver's licenses and automobile registrations, so long as the checks follow an established pattern or there are specific grounds for a departure from the pattern. Routine inspection of passengers and carry-on luggage has been upheld as a regulatory measure to prevent airplane hijacking. In these cases, not only is the procedure in question thought to be less objectionable than a full search; there is no way to accomplish the legitimate objective of the procedure consistently with a requirement of a warrant.
The Fourth Amendment does not insist that persons protect a privacy that they are willing to forego. Accordingly, a warrant to search is not required if a person having authority to do so voluntarily admits public officials and permits them to search. A consensual search that is successful often is challenged later on the grounds that consent was not given fully voluntarily or did not extend to the actual search; or, if the premises are shared by others, it may be claimed that the person who consented did not have the independent authority to do so. While a resolution of such issues may depend on difficult matters of fact, the basic principle that a search with consent does not require a warrant is unquestioned.
Those who believe that the requirement of a search warrant is a significant protection against unreasonable searches may conclude that the Supreme Court has drawn the categories of lawful warrantless searches too broadly. Categories like the search incident to arrest, automobile search, and jail search appear to depend only on the premises that such searches often are fruitful and sometimes have to be made before a warrant can be obtained. But the categories are general and require neither premise to be fulfilled in the particular case; each of them encourages the police to make a large number of searches routinely, without particular justification. This approach, it can be argued, is inconsistent with the plain purpose of the Fourth Amendment to prohibit general searches: unfocused, unlimited rummaging in the privacy of individuals.
Critics of the Court have observed also that its analysis of warrantless searches is to a considerable degree incoherent. Why, for example, should an arrest justify the search of any area surrounding the arrestee, if he can be and often is removed from that place before the search is made? Why should automobiles, which often are used for the same private purposes as dwellings, be treated categorically as less private? Why should an arrest automatically defeat the person's separate interest in the privacy of items in his possession? The Court's failure to provide convincing answers to such questions has rendered this part of Fourth Amendment doctrine only a set of rules without supporting rationale.
A defense of the rules for warrantless searches begins with the premise that warrants are peculiarly appropriate for planned investigative searches and have much less utility in the ordinary unplanned encounters between police or other public officials and private persons. If legitimate police duties justify an encounter, then a search related in purpose is also legitimate. This approach places a great deal of emphasis on the requirement that a search be "reasonable" and construes that term with attention to common police practices as well as the individual interest in privacy. To limit warrantless searches to cases of manifest necessity would blink the natural—and therefore reasonable—impulse of police officers to search whatever is legitimately in their custody and may furnish evidence of crime. Some explanation for the breadth of the exceptions to the requirement of a warrant may lie also in the fact that the issue is almost always tested in the context of a criminal prosecution, when the defendant seeks the protection of the exclusionary rule to avoid the admission of incriminating evidence that a search has uncovered.
Lloyd L. Weinreb
American Law Institute 1975 A Model Code of Pre-Arraignment Procedure. Philadelphia: American Law Institute.
Amsterdam, Anthony G. 1974 Perspectives on the Fourth Amendment. Minnesota Law Review 58:349–477.
Weinreb, Lloyd L. 1974 Generalities of the Fourth Amendment. University of Chicago Law Review 42:47–85.