The Right to Privacy

The word “privacy” does not appear in the U.S. Constitution, but the U.S. Supreme Court has said that several of the amendments create this right. One of these is the Fourth Amendment. It stops the police and other government agents from searching citizens or their property without facts or apparent facts that are reliable and generate a belief that incriminating evidence can be found on the citizens or the property. Justice Louis Brandeis called the right to privacy “the right to be left alone by the government.” Calling this right the most valuable of all rights, Brandeis considered “every unjustifiable intrusion by the government upon the privacy of the individual” to be a violation of the Fourth Amendment.


For police action to be brought under the protection of the right to privacy, it must be considered to be a search. A search involves police actions designed to find, ascertain, or recover evidence of crimes, weapons, and contraband. Common targets of searches include homes, papers, effects, and persons suspected of criminal involvement. Examples of searches include looking inside a container in a car, taking blood and urine samples, and wiretapping.

Search warrants

Once an act of a police officer is determined to be a search, the next question is “Was it reasonable?” The general rule of the Fourth Amendment is that any search or seizure undertaken without a valid search warrant is illegal. A search warrant is a written order from a judge directing the police to search a specific place for particular persons or items to be seized. The objects sought may include drugs, stolen goods, burglars' tools, weapons, or other items kept or concealed in violation of the law.

The standard of proof for a search warrant

For searches and seizures, the Fourth Amendment requires the government to show probable cause. Probable cause consists of facts that would lead a reasonable police officer to believe that the places or persons to be searched will yield the contraband, fruits of a crime, persons, weapons, or other items named in the warrant. As a standard of proof, probable cause requires more than mere suspicion but less than legal guilt (proof beyond a reasonable doubt).

Particularity of search warrants

The Fourth Amendment requires that a search warrant describe with “particularity” the place to be searched and the things—either people or objects—to be seized.

How the police obtain and execute a search warrant

Before going to a judge to get a warrant, an officer must prepare an affidavit, which gives a detailed description of the place to be searched and the persons or things to be seized. Next, the officer swears under oath that the information in the affidavit is truthful. Then, the officer tries to convince a judge that the information amounts to probable cause to believe that contraband or other evidence is in a specific place.

The Gates test

In deciding whether or not to authorize a search, a judge applies the Gates test. The Supreme Court's ruling in Illinois v. Gates (1983) lowered the evidentiary requirements for probable cause in search warrant applications. Prior to Gates, the rule was that probable cause for search couldn't be based solely on hearsay (secondhand) information. In Gates, the Court made it easier for police to satisfy the evidentiary requirements for a search warrant. It required judges to simply make a common‐sense decision, given all the circumstances set forth in an affidavit, that there is a fair probability that incriminating evidence can be found in a particular place.

After a judge issues a warrant, the police must execute it promptly because the suspect may move or destroy the evidence The Federal Rules of Criminal Procedure set a limit of ten days within which the police must carry out a search. States establish similar deadlines.

No-knock warrants

A no‐knock warrant authorizes police to break down doors without warnings and to enter homes or public places. The Supreme Court has ruled that no‐knock warrants can be used when police fear that announcing their presence could endanger their lives or give criminals time to destroy the evidence the police are seeking. Civil liberties advocates think no‐knock warrants often violate the spirit of the Fourth Amendment because they are often based on unreliable sources of information. No‐knock warrants are sometimes based solely on the word of confidential informers, who are often criminals seeking to trade what they know for reduced charges, shorter sentences, or cash. Police officials defend no‐knock warrants, saying the warrants have enabled the police to mount an aggressive assault against drugs. Moreover, the police assert that a majority of their no‐knock search warrants yield contraband.

Electronic eavesdropping as a search

Electronic eavesdropping is considered a search. It consists of both telephone wiretapping and bugging. (Bugs are electronic listening devices that record sounds.) Law enforcement agents sought a record number of court orders in 1997 to allow them to secretly listen in on more than two million private conversations. The telephone wiretap was the most common device used. Narcotics investigations spurred almost 75 percent of the wiretap requests in 1997. The most common location for the placement of wiretaps in 1997 was a single‐family dwelling.

Conditions under which the government can use electronic eavesdropping

Title III of the federal Omnibus Crime Control and Safe Streets Act (1968) places wiretapping and bugging under tight controls. Under this law, police must get a search warrant before secretly intercepting conversations. Title III contains a statutory exclusionary rule. It prohibits trial courts, grand juries, regulatory agencies, and other government bodies from using evidence obtained by unauthorized interception.

Searches without warrants

An exception to the warrant requirement in Title III applies to officers who are parties to conversations: they don't need a warrant to wear a wire or tape a phone call. The Supreme Court has determined that exigent circumstances (in other words, emergencies and other situations requiring exceptional police actions) justify exceptions to the warrant rule. In reality, most police searches are conducted without warrants. The majority of warrantless searches fall into one of the following categories.

  • Consent search: A consent search is a warrantless search made when the person in control of an area or object gives his or her consent. By consenting, a citizen forfeits all Fourth Amendment rights. Most criminal charges are handled through consent searches. A citizen must voluntarily consent, rather than being coerced or tricked into consenting. A citizen always has the right to say “no.” Police are not legally obligated to inform citizens whose consent they are seeking that citizens have a right to refuse to give consent.

  • Hot‐pursuit search: A hot‐pursuit search is a warrantless search following an officer's chase of a dangerous suspect into the suspect's home, the residence of a third party, a public building, or some other place.

  • Automobile search: An automobile search is a warrantless search of a car when police have probable cause to believe the car contains evidence of a crime. The Court permits officers to search cars more freely than houses. Due to the mobility of cars, officers may give up opportunities to seize evidence if they take the time to get a warrant. The police can't, however, simply begin searching a car because they are suspicious of the driver's appearance. To satisfy the probable cause prerequisite, the police must have prior knowledge that the vehicle was involved in a crime or contains contraband. In a rare win for privacy rights, the Court ruled in Knowles v. Iowa (1998) that police can't search people and their cars after merely ticketing them for routine traffic violations. Such a search—without suspicion of other wrongdoing—is unreasonable and unconstitutional. The Court's decision in Knowles ran counter to its trend since the 1970s of narrowing the privacy rights afforded by the Fourth Amendment.

  • Search incident to arrest: Once there is probable cause to make an arrest, the Court said in U.S. v. Robinson (1973), a police officer can search the person arrested and the area under the arrestee's control. It makes sense, the Court said, to authorize such a search to preserve evidence and to protect the arresting officer's safety.

  • Plain‐view search: A warrantless plain‐view search, which takes place when a police officer sees evidence in plain view, is legal so long as the officer has a right to be present in the place where he or she discovers the evidence. If an officer has a warrant to search a house for guns, for example, and finds illegal drugs during the search, the officer can also seize the drugs. Under the protective sweep doctrine, the conservative Court expanded the scope of plain view. A protective sweep is a quick, limited, warrantless search of the entire premises. If police have reasonable suspicion that others are on the premises when they arrest a suspect, the officers can examine the entire premises. If the police have no suspicion that there are others in a place where they make an arrest, they can still look into adjoining closets or rooms. In both situations, the police may seize contraband or evidence in plain view.


Under the Fourth Amendment, an arrest is a seizure. Legally, an arrest occurs when the police take a citizen into custody for the purpose of charging that citizen with a crime. Administratively, an arrest involves booking. Law enforcement officers take the arrestees to a police station where they fingerprint, photograph, and record identifying information about the suspects.

The standard of proof for an arrest

Police make most arrests without warrants. For a warrantless arrest to be constitutional, the arresting officer must have probable cause, which means that officers must reasonably believe that a suspect is about to commit or has committed a crime. Probable cause can be based on either direct evidence (that is, first‐hand information that is personally known to police officers) or hearsay. When there is no immediate need to arrest a suspect, the police may seek a court order, commonly called an arrest warrant. To obtain the arrest warrant, a police officer must submit to a judge an affidavit containing evidence in support of probable cause. The judge must review the affidavit and decide whether or not to issue an arrest warrant. In the majority of felony cases, though, a police officer will act without a warrant and will make that arrest as soon as he or she is convinced that there are grounds to do so.

The basic rules of arrest

Under common law, a police officer may arrest a person for a felony when the officer has probable cause to believe that a crime has been committed and that the suspect committed the crime. For a misdemeanor arrest, however, the offense must occur in the presence of an officer before the officer can make an arrest. The general rule is that a citizen complaining about another citizen's commission of a misdemeanor must seek a judicially authorized arrest warrant before a police officer can make a misdemeanor arrest. This rule has caused problems in some areas such as domestic abuse. It has prevented police from making arrests at the scene of spouse abuse where a spouse accuses her partner of committing a simple assault. To correct the problem, legislatures have revised the rules for misdemeanor arrests that relate to domestic violence and other similar crimes.

Necessity for arrest warrants

An arrest warrant is a document that a court issues ordering law enforcement officers to take a specific individual into custody. Under certain circumstances, the police must have a warrant to make an arrest. In public places, the police can arrest a felon without a warrant if they have probable cause. In homes, police must have a warrant to make a routine felony arrest. In some situations, exigencies (such as the hot pursuit of a dangerous felon) allow the police to engage in warrantless arrests in homes.

Arrests and domestic violence

For many years, the police handled domestic violence cases differently from other assaults. They hesitated to make arrests in domestic abuse cases, not wanting to intervene in private matters between a man and a woman. A federal court eventually held this gender‐based policy to be in violation of the Fourteenth Amendment. In the 1970s, legislatures passed mandatory arrest laws for domestic abuse. The Minneapolis experiment showed that making mandatory arrests of the battering partner reduces levels of domestic violence more than mediating disputes or separating couples. The finding that arrest deters spousal abuse spurred other police departments to adopt mandatory arrest policies. Replication studies in other cities have found a deterrent effect of mandatory arrest, but only under certain conditions.


A stop is a Fourth Amendment seizure. The police often stop and question people without having enough facts to justify an arrest or search. Until the late 1960s, police exercised total discretion in deciding who, when, where, and how to conduct stops.

Stop and frisk

Police have a right to temporarily stop individuals whose behavior seems suspicious, to detain them briefly for questioning, and to pat them down. Stop and frisk is justified on the grounds of crime control and public safety. In Terry v. Ohio (1968), the Supreme Court held that when a police officer observes “unusual conduct” that leads him or her to think that criminal activity “may be afoot,” the officer can search the outer clothing of the suspect to discover weapons. Such a search, the Court said, must be based on reasonable suspicion. If officers suspect that an individual may be committing, may be about to commit, or may have committed a crime, they can stop, question, and pat down the individual. Reasonable suspicion is a lower standard of evidence than probable cause. The Court reasoned that since a stop is a lesser deprivation of freedom than an arrest and stop and frisk is less intrusive than a full‐body search, stops require fewer facts than probable cause. A police officer does not have to directly observe the facts upon which reasonable suspicion is based. Hearsay and/or an anonymous tip can be the basis of suspicion.

Drug stops

Drug Enforcement Administration agents and other police closely watch airports, bus stations, and interstate highways for people who may be transporting illegal drugs. Sometimes drug enforcement agents base their stops of suspected drug traffickers on tips from informants. Many times, however, the agents stop people like Joe Morgan who fit a drug courier profile, a set of factors, that taken together, identify drug runners based on their personal characteristics, mannerisms, and modus operandi, or general method of operation. Acting on reasonable suspicion of drug possession, police can briefly stop and question individuals to find out if they are carrying drugs.

Critics contend that profiles discriminate against racial minorities. Some studies support this claim. For example, a 1997 study found that African‐American motorists stopped on the Florida Turnpike by an all‐white Orange County (Orlando) sheriff's drug enforcement squad were six and a half times more likely to be searched than white drivers. Forty percent of the black motorists were searched, while only 6 percent of the whites were searched. Researchers explained these disparities in terms of the belief on the part of the police that blacks are more likely than whites to be trafficking in cocaine on Florida highways.

Are such racially biased search procedures legal? Even though the Supreme Court upheld the constitutionality of drug courier profiles in U.S. v. Sokolow (1989), Justice Thurgood Marshall's dissent pointed out serious flaws in profiles. Marshall disagreed with the majority's ruling that the reasonable suspicion level of proof is met simply by the police identification of a suspect as having characteristics that fit a drug courier profile. Once the police establish this level of proof, the Court declared, a Terry stop is permissible. Marshall demonstrated the falsity of this premise in the majority's argument by pointing out that the Terry rule requires evidence of ongoing criminality—such as casing a store before robbing it—to establish reasonable suspicion. As Marshall noted, most profiles do not meet such a standard.

Marshall also challenged the validity of drug courier profiles. From journalistic reports, it appears that the “hit,” or success, rate of these profiles (in other words, correct predictions that a person is indeed transporting drugs) is no better than the results that could be obtained by flipping a coin (in other words, 50 percent). Even worse, some profiles include a race/ethnicity factor which makes them racially biased and violative of the equal protection clause of the Fourteenth Amendment.