Most constitutional constraints on police and prosecutors derive from the Fourth, Fifth, and Sixth Amendments. These amendments regulate the conduct of the federal government and its agents directly. With the exception of the Fifth Amendment grand jury requirement, provisions of these amendments governing criminal procedure are “incorporated” to the states via the due process clause of the Fourteenth Amendment, and therefore regulate state governments and their agents as well.
For most of its history, the Fourth Amendment was understood to regulate physical intrusions. Thus, in Olmstead v. United States, 277 U.S. 438 ( 1928 ), the Supreme Court held that wiretapping a suspect's phone was not a “search” under the Fourth Amendment because “[t]here was no entry of the houses or offices of the defendants.” That changed in 1967 with the Court's decision in Katz v. United States, 389 U.S. 347 ( 1967 ), which held that eavesdropping on telephone conversations using an electronic device attached to a public phone booth violates reasonable expectations of privacy and therefore constitutes a Fourth Amendment “search.”
Katz gave rise to several very important doctrines. According to the public observation doctrine, officers may observe anything that can be seen from a lawful vantage point without implicating the Fourth Amendment. Thus police may track the public movements of a suspect using a beeper tracking device ( United States v. Knotts, 460 U.S. 276  ), look into the backyard of a home from a low-flying aircraft ( Florida v. Riley, 488 U.S. 445  ), or use a telephoto lens to make observations from a distance ( Dow Chemical Co. v. United States, 476 U.S. 227  ). The third-party doctrine allows government agents to access through lawful means information shared with third parties without implicating the Fourth Amendment. This doctrine covers cases of misplaced trust, such as when officers use confidential informants ( Hoffa v. United States, 385 U.S. 293  ); business records, including bank transaction logs ( California Bankers Assn. v. Shultz, 416 U.S. 21  ); and telephone call registries ( Smith v. Maryland, 442 U.S. 735  ). In United States v. Jones, 565 U.S. ___ ( 2012 ), several justices indicated that these doctrines may need to be revised in light of advanced surveillance and data aggregation technologies.
According to its text, and read for its original public meaning, the Fourth Amendment does not impose a general warrant requirement ( Amar 1997 ). Nevertheless, the Court has held consistently that searches of homes, persons, and similar highly protected areas require warrants ( Agnello v. United States, 269 U.S. 20  ). Arrests (seizures of persons) made in an arrestee's home also require a warrant ( Payton v. New York, 445 U.S. 573  ). Pursuant to the warrant clause, only detached and neutral magistrates may issue warrants, and only where investigators demonstrate probable cause to believe that specific evidence of a crime will be found in a particular place at the time of the search. Searches of highly protected places conducted without a warrant, pursuant to a defective warrant, or outside the scope of a lawful warrant, are presumed to be unreasonable ( Johnson v. United States, 333 U.S. 10  ). This presumption does not apply if police have lawful consent to conduct a search ( United States v. Matlock, 415 U.S. 164  ), a search is conducted under exigent circumstances ( Warden v. Hayden, 387 U.S. 294  ), or the purpose of a search is to advance compelling “special needs” unrelated to a criminal investigation ( New York v. Burger, 482 U.S. 691  ). As a general matter, searches of cars require probable cause, but do not require a warrant ( California v. Carney, 471 U.S. 386  ); the same is true of arrests in public ( Gerstein v. Pugh, 420 U.S. 103  ). In both circumstances, however, a search or seizure will be subjected to prompt, post hoc judicial review at a probable cause hearing.
Officers engaged in a search must conduct themselves reasonably ( Hummel-Jones v. Strope, 25 F.3d 647 [8th Cir. 1994] ). Search warrants must be served when mthe probable cause upon which they are based is “ripe” ( United States v. Grubbs, 547 U.S. 90  ). Before entering a premises, officers must knock, announce themselves, and provide occupants a reasonable opportunity to cooperate, unless this procedure would unreasonably compromise officer safety or the security of evidence ( Wilson v. Arkansas, 514 U.S. 927  ). Once on a premises, officers may only search in locations described in the warrant and in places where evidence named in the warrant is likely to be found ( United States v. Evans, 92 F.3d 540 [7th Cir, 1996] ). During a lawful search, officers may seize any evidence that is in “plain view,” even if not named in the warrant ( Horton v. California, 496 U.S. 128  ).
Searches and seizures not subject to the warrant requirement must be “reasonable.” This requires striking a balance between governmental needs, including preserving evidence and detecting, investigating, and prosecuting crime, and citizen interests in privacy, property, and physical security ( United States v. Place, 462 U.S. 696  ). Reasonableness is a fact-intensive, case-specific analysis, seldom amenable to bright line rules ( Scott v. Harris, 550 U.S. 372  Chimel v. California, 395 U.S. 752  ). This search incident to arrest rule does not encompass the contents of smartphones; officers must secure a warrant before searching these devices ( Riley v. California, 573 U.S. ___  ).
A common circumstance where courts review searches and seizures for reasonableness is in the context of street encounters. In Terry v. Ohio, 392 U.S. 1 ( 1968 ), the Supreme Court held that, where police officers have reason to suspect that a target is engaged in criminal activity, they may conduct a brief stop to confirm or dispel their suspicions, and where officers have reason to suspect that a target is carrying a weapon, they may conduct a brief pat-down or “frisk” of his outer clothing in search of weapons.
The primary means of enforcing the Fourth Amendment in criminal trials is the exclusionary rule, which provides that illegally seized evidence will be excluded from the prosecution's case in chief, which is where the prosecutor presents her evidence, along with any investigative proceeds of that evidence, which are referred to as “fruits of the poisonous tree” ( Wong Sun v. United States, 371 U.S. 471  ). This was not always true. Until the late eighteenth century, the only remedy available for Fourth Amendment violations was a private tort action ( Amar 1997 ). In fact, courts roundly refused to apply anything like the exclusionary rule ( United States v. La Jeune Eugenie, 26 F. Cas. 832, 843–44 [C.C.D. Mass. 1822] ); Commonwealth v. Dana, 43 Mass. [2 Met.] 329, 337 ). That began to change with the Supreme Court's decision in Boyd v. United States, 116 U.S. 616 ( 1886 ), which relied on the Fifth Amendment privilege against compelled self-incrimination to forbid government exploitation of illegally seized papers and their contents. In Weeks v. United States, 232 U.S. 383 ( 1914 ), the Court held that the Fourth Amendment itself required exclusion of illegally seized evidence. The Supreme Court incorporated the exclusionary rule to the states in Mapp v. Ohio, 367 U.S. 643 ( 1961 ).
The exclusionary rule is subject to several important exceptions. Only defendants whose Fourth Amendment rights are violated may seek exclusion. Illegally seized evidence may therefore be admissible against others, including codefendants ( United States v. Payner, 447 U.S. 727  ). Evidence will be excluded only if its discovery is caused by a Fourth Amendment violation. Prosecutors may therefore avoid exclusion if they show that challenged evidence inevitably would have been discovered by legal means ( Segura v. United States, 468 U.S. 796  ). The exclusionary rule does not apply if investigating officers act in “good faith” by, for example, searching under the authority of a warrant later determined to be infirm ( United States v. Leon, 468 U.S. 897  ). The exclusionary rule also does not apply in collateral forums such as grand jury investigations ( United States v. Calandra, 414 U.S. 338  ), civil tax suits ( United States v. Janis, 428 U.S. 433  ), immigration proceedings ( Immigration and Naturalization Service v. Lopez-Mendoza, 468 U.S. 1032  ), and parole revocation hearings ( Pennsylvania Board of Probation and Parole v. Scott, 524 U.S. 357  ).
The pertinent portions of the Fifth Amendment provide that:
No person shall be held to answer for a capital, or otherwise infamous, crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law …
The grand jury clause of the Fifth Amendment is among the few constitutional rights not incorporated to the states ( Hurtado v. California, 110 U.S. 516  ). Many states follow the federal model, requiring a grand jury indictment for serious crimes, but they are not under any Fifth Amendment mandate.
The double jeopardy clause protects defendants from being tried and punished more than once for the same conduct by the same sovereign. This has two principal applications. First, the Fifth Amendment prevents prosecutors from retrying defendants who have been acquitted or otherwise put in prior jeopardy of punishment ( United States v. DiFranceso, 449 U.S. 117  ). “Jeopardy” attaches at the commencement of trial, usually with the swearing in of a jury ( Crist v. Bretz, 437 U.S. 28  ). Second, the Fifth Amendment prevents defendants convicted of both a principal offense and a lesser, but included, offense from being sentenced separately for each crime ( Brown v. Ohio, 432 U.S. 161 1977] ). Double jeopardy generally does not cross jurisdictions. Therefore, defendants whose crimes may be subject to both state and federal prosecution can be tried, convicted, and punished in both jurisdictions for the same conduct ( United States v. Lanza, 260 U.S. 377  ).
The Fifth Amendment privilege against compelled self-incrimination is principally a trial right ( United States v. Patane, 542 U.S. 630  ). Adopted in the historical shadow of religious and political inquisitions, it protects defendants from the “cruel trilemma” of selfincrimination, perjury, and contempt ( Pennsylvania v. Muniz, 496 U.S. 582  ). However, a defendant who chooses to take the stand in his own defense generally may not “plead the Fifth” when subjected to crossexamination. The Fifth Amendment also bars the admission of “testimonial” statements made by defendants outside the courtroom and in response to police questioning ( Schmerber v. California, 384 U.S. 757  ). This includes statements secured in violation of Miranda v. Arizona, 384 U.S. 436 ( 1966 ).
The due process clauses of the Fifth and Fourteenth Amendments secure many procedural and substantive rights for criminal defendants. Among the most important of these are prohibitions on the state's use of perjured testimony ( Mooney v. Holohan, 294 U.S. 103  ), the right to receive exculpatory evidence in the possession of law enforcement ( Brady v. Maryland, 373 U.S. 83  )—including evidence that might be used to impeach government witnesses ( United States v. Bagley, 473 U.S. 667  Brown v. Mississippi, 297 U.S. 278  ).
The Sixth Amendment provides that:
In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the State and district wherein the crime shall have been committed, which district shall have been previously ascertained by law, and to be informed of the nature and cause of the accusation; to be confronted with the witnesses against him; to have compulsory process for obtaining witnesses in his favor, and to have the Assistance of Counsel for his defence.
By its language, the Sixth Amendment applies only to “criminal prosecutions.” The line between criminal cases and civil cases is not always obvious. For example, many states have civil commitment provisions for convicted sex offenders. Courts generally trust legislative designations of sanctions as “civil” rather than “criminal” unless faced with the “clearest proof that the statutory scheme is so punitive either in purpose of effect as to negate the State's intention to deem it civil” ( Kansas v. Hendricks, 521 U.S. 346, 361 ; internal citation, quotation marks, and alterations omitted ).
The right to a speedy trial “is as fundamental as any of the rights secured by the Sixth Amendment” ( Klopfer v. North Carolina, 386 U.S. 213, 223  ). The Supreme Court has identified three primary interests at stake in the right to speedy trial: (1) deprivation of liberty; (2) the opportunity to challenge public allegations of criminal wrongdoing; and (3) the impact of delay on the defense ( Smith v. Hooey, 393 U.S. 374  ). The right to speedy trial attaches at arrest or the public filing of formal charges, whichever comes first ( United States v. Marion, 404 U.S. 307  ). When determining whether the right to a speedy trial has been violated, courts apply a balancing test weighing length of delay, reason for delay, whether and when the defendant demanded a prompt trial, and prejudice caused by the delay ( Barker v. Wingo, 407 U.S. 514  Strunk v. United States, 412 U.S. 434  ).
In response to abuses perpetrated by secret tribunals, including the Star Chamber, late-eighteenth-century English common law guaranteed the right to a public trial. The Sixth Amendment encompasses that common law right, relying on publicity to help curb abuses by courts and prosecutors, to provide notice to potential witnesses so they might come forward, and to inhibit perjury ( In re Oliver, 333 U.S. 257  ). The right is not absolute—limited closure is allowed if necessary to protect victims, witnesses, or state secrets ( Waller v. Georgia, 467 U.S. 39  ).
The right to trial by jury traces back at least as far as Magna Carta and is meant to prevent government oppression by “corrupt or overzealous prosecutor[s] and … compliant, biased, or eccentric judge[s]” ( Duncan v. Louisiana, 391 U.S. 145, 156  ). The Sixth Amendment right to a jury trial applies to all cases involving more than mere “petty” offenses ( Baldwin v. New York, 399 U.S. 66  ). Although common law juries generally consisted of twelve members, the Supreme Court in Williams v. Florida, 399 U.S. 78 1970), upheld the use of six-member juries. In Apodaca v. Oregon, 406 U.S. 404 ( 1972 ), the Court also loosened common law requirements that guilty verdicts be unanimous, allowing convictions based on supermajorities of twelve-person juries. The Court in Burch v. Louisiana, 441 U.S. 130 ( 1979 ), however, preserved the unanimity requirement for smaller juries.
The Sixth Amendment does not guarantee defendants the right to any particular composition of petit juries ( Fay v. New York, 332 U.S. 261 ; Holland v. Illinois, 493 U.S. 474  ). It does, however, guarantee that the jury venire, from which a petit jury is chosen, will represent a “fair cross-section” of the population within a jurisdiction ( Taylor v. Louisiana, 419 U.S. 522 1975] ). During the jury selection process, parties may strike potential jurors peremptorily or for cause. The use of these challenges is governed by the equal protection clause of the Fourteenth Amendment ( Batson v. Kentucky, 476 U.S. 79  ).
For many years, the Sixth Amendment right to confront witnesses at trial was determined in part by reference to established evidentiary rules governing the admissibility of hearsay. That changed with the Court's decision in Crawford v. Washington, 541 U.S. 36 ( 2004
By its text and history, the Sixth Amendment guaranteed a right to privately retained counsel in all criminal proceedings but probably was not understood as providing a right to appointed counsel. In Powell v. Alabama, 287 U.S. 45 ( 1932 ), the Supreme Court began to shift that understanding, holding that due process requires states to provide appointed counsel for indigent defendants in capital cases. Johnson v. Zerbst, 304 U.S. 458 ( 1938 ), went further, holding that the Sixth Amendment guarantees access to appointed counsel in all federal prosecutions. Gideon v. Wainwright, 372 U.S. 335 ( 1963 ), incorporated that rule to the states, requiring that states and localities provide appointed counsel for indigent defendants in all cases where the potential punishment is greater than six months in jail or a fine of $500. The right to counsel attaches at the commencement of adversarial proceedings, which usually is marked by the filing of formal charges ( Massiah v. United States, 377 U.S. 201  ).
The Fourth, Fifth, and Sixth Amendments establish important rules governing searches and seizures and the prosecution of criminal cases. In so doing, these provisions set important constraints on governmental power and the exercise of that power. These constraints were regarded as critical to the Founders and continue to play a central role in engagements between citizens, police, and prosecutors.
SEE ALSO Capital Punishment ; Criminal Law ; Exclusionary Rule ; Fourteenth Amendment ; Fourteenth Amendment: Due Process Clause ; Fourth Amendment ; Incorporation of the Bill of Rights ; Police Powers ; US Bill of Rights .
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Francis King Carey School of Law University of Maryland
Francis King Carey School of Law University of Maryland