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Due Process and Justice

Due process is a fundamental constitutional guarantee of the United States justice system, and a principle discussed recently in the news in relation to several high-profile cases springing from Special Counsel Robert Mueller’s investigation of Russian interference with the 2016 presidential election. It is a right of the accused that the accuser must adhere to as they seek to prove the guilt or innocence of an aggrieved party. But what exactly is due process, and why is it seen as a central tenant of justice and the preservation of liberty? In this eLesson, students will explore the principle of due process through an examination of the exclusionary rule and the Supreme Court case of Mapp v Ohio (1962).


  • Students will understand due process and its relationship to both liberty and justice
  • Students will evaluate the case of Mapp v Ohio and its relationship to due process


  • Handout A: Definition of Due Process
  • Handout B: Case Background of Map v Ohio
  • Handout C: Excerpt: Majority Opinion Mapp v Ohio

Lesson: Warm-up Activity – 5 minutes Directions: Have students read Handout A: Definition of Due Process or write the Definition of Due Process on the board. As a class or individually, have your students answer the two review questions.

Activity: Mapp v Ohio (1962) – 15-20 minutes Directions: Individually or in small groups, have your students read

Handout B: Case Background: Mapp v Ohio (1962) and Handout C: Excerpt: Majority Opinion Mapp v. Ohio, and answer the review questions.

Wrap-up Activity – 5 minutes Directions: Have your students share their responses to the review questions. Lead them in a class discussion about the exemption rule and its relationship to due process. Ask them to assess the claim that the exclusionary rule helps ensure liberty and justice.

Handout A: Due Process defined Due Process: Government must interact with all citizens according to the duly enacted laws, applying these rules equally among all citizens. Review questions:

  • In your own words, define due process.
  • Do you think due process is central to the protection of individual liberty? Why or why not?

Handout B: Case Background: Mapp v. Ohio (1962) The Fourth Amendment protects individuals from unreasonable searches and seizures and requires two branches of government to agree in order for search warrants to be issued. But what happens when the police do not act within the law and conduct searches without a warrant? The Fourth Amendment does not specify. In a series of cases, the Court was asked to consider whether criminal defendants’ convictions could stand if illegally-seized evidence was used against them in Court. In the 1914 case of Weeks v. United States, the Court answered no. With this ruling, the Court established the exclusionary rule for federal cases: evidence seized in violation of the Constitution may not be used at trial. Among the early critics of the exclusionary rule was Appeals Court Judge Benjamin Cardozo. Cardozo famously objected in 1926, “The criminal is to go free because the constable has blundered.” About thirty-five years later in 1949, the Court declined to apply the exclusionary rule to the states through the Fourteenth Amendment’s Due Process Clause, reasoning that states could use other methods of ensuring due process of law. When Mapp v. Ohio reached the Court in 1961, it was not initially seen as a Fourth Amendment case. Dollree Mapp was convicted under Ohio law for possessing “lewd, lascivious, or obscene material.” Mapp appealed her conviction. She based her claim on First Amendment grounds, saying that she had a right to possess the materials. When the case reached the Supreme Court, however, the Justices did not address her First Amendment claim. The Court instead overturned her conviction because the evidence against her had been seized without a warrant. In so ruling, the Court applied the exclusionary rule to the states. The exclusionary rule remains controversial. Supporters say it ensures liberty and justice, while critics claim it actually threatens those values. Review Questions:

  • What is the “Exclusionary Rule”? Provide a short definition
  • How does the Exclusionary Rule relate to Due Process?
  • What are some objections to the use of the Exclusionary rule?
  • Do you think these concerns are fair or over stated?
  • The case of Mapp v. Ohio dealt, not with the establishment of the federal exclusionary rule, but with its incorporation to the States through the due process clause of the 14th Why do you think the court saw the exclusionary rule as necessary to preserving an individual’s right to due process at the state level?

Handout C: Excerpt: Majority Opinion (6-3) Mapp v Ohio (1962) There are those who say … that under our constitutional exclusionary doctrine “[t] he criminal is to go free because the constable has blundered.” …[And] in some cases this will undoubtedly be the result. But…there is another consideration- the imperative of judicial integrity. …The criminal goes free, if he must, but it is the law that sets him free. Nothing can destroy a government more quickly than its failure to observe its own laws, or worse, its disregard of the charter of its own existence. Our decision, founded on reason and truth, gives to the individual no more than that which the Constitution guarantees him, to the police officer no less than that to which honest law enforcement is entitled, and, to the courts, that judicial integrity so necessary in the true administration of justice. Review Questions:

  • How does the court explain its decision?
  • How does the court anticipate challenges to its ruling?
  • How does the courts ruling connect to due process?
  • Do you agree or disagree with the courts majority opinion? Explain your answer.

Extension: For a full treatment of Mapp v. Ohio see the Bill of Rights Institute’s lesson on Voices of History!