Policing: Understanding Case Law

case-law“When I worked in the Department of Justice, in the office of the solicitor general, it was my job to argue cases for the United States before the Supreme Court. I always found it very moving to stand before the justices and say, I speak for my country”. – John G. Roberts Jr., 17th Chief Justice of the United States

Case Law

Case law is defined as the law as established by the outcome of court case decided by the courts and an explanation of how the decision was made based on law (USC, 2015). The new ruling becomes precedent established by judicial decisions (court ruling) instead of by a legislative act of Congress or a particular state legislative body (USC, 2015).

The legal definition of stare decisis is the policy of the courts to follow rules laid down in previous higher court rulings (USC, 2015). Stare decisis in the concept that the courts will maintain that previous decisions handed down by higher courts and the ruling must be followed when deciding cases or applying legal protocols (USC, 2015). In simple terms, when the Supreme Court of the United States makes a ruling and issues a decision on a case the lower courts must adhere to the legal interpretation of the higher courts and follow the new ruling as law (USC, 2015). These ruling often change policy on how lower courts will decide on a case and change law enforcement policies, tactics, and strategies to follow the new court decision (USC, 2015).

Miranda WarningOne of the most famous Supreme Court of the United States ruling was that of Miranda v. Arizona (1966) (Facts and Case Summary – Miranda v. Arizona, 2015). This case insured that anyone that law enforcement places in a custodial situation must be read the “Miranda Warning” against self-incrimination before a lawfully obtained confession that will be admissible in court is allowed (Facts and Case Summary – Miranda v. Arizona, 2015). If the suspect wishes to have a lawyer present during question law enforcement officers must stop asking questions, until a lawyer is present (Facts and Case Summary – Miranda v. Arizona, 2015). The Miranda Rights has become part of American culture on police television series and in the movies. It is common knowledge in American society after you are arrested to be read the Miranda Rights. It is important to note that the Miranda Warnings are given sometime during the initial arrest and first appearance to determine bail. If the officer is not going to question you about criminal activity, the Miranda Rights are not needed.

Terry_vs._Ohio_3The Terry v. Ohio, 391 U.S. 1 (1968) case ruling create the “Terry Pat-Down” or “Terry Search” (Supreme Court Landmarks, 2015). The Supreme Court of the United States ruled that police officers could conduct a frisk of a person if there is reasonable suspicion that the person being detained is committing, or has committed, a crime (Supreme Court Landmarks, 2015). For the frisk of the person to be lawful, the officer must suspect the person is armed and possibility dangerous (Supreme Court Landmarks, 2015). The Terry Pat-Down is only to check for weapons on the outer garments and not a complete invasive body search such as pockets turned inside out (Supreme Court Landmarks, 2015). Officers can quickly violate lawful searchers if using “Terry” and they are looking for more than just weapons.

come-back-with-a-warrant (2)Mapp v. Ohio, (1961) case established that the “exclusionary rule” was applied to the states as well as the federal government (Supreme Court Landmarks, 2015). The courts had previously ruled in Weeks v. United States (1914) that illegally obtained evidence in federal court could not be used as evidence; however, Mapp v. Ohio, (1961) this was the first time the courts ruled that it also applied to each state (Supreme Court Landmarks, 2015). The exclusionary rule states that any evidence obtained illegally in violation of someone’s rights cannot be used in trial against them (Supreme Court Landmarks, 2015). The courts in their ruling used the metaphor, the “fruit of the poisonous tree” to describe illegally obtained evidence in violation of U.S. Constitution protections of individual rights (Supreme Court Landmarks, 2015). For example, law enforcement cannot use a confidential informant to break into a house, take a marijuana plant, bring the marijuana back to the officers as evidence, and then the officers arrest the homeowner for possession of marijuana. The evidence was obtained illegally even if was from a law enforcement informant/agent. Evidence must be obtained legally within the framework of the 4th Amendment to the U.S. Constitution to be admissible in court.

group-1-carmo-musaschio-friedman-5-728Carroll v. United States (1925) case established the “Carroll Doctrine” in which the Supreme Court of the United States decision upheld that a warrantless search of an automobile was lawful (Supreme Court Landmarks, 2015).  The Carroll Doctrine exception is given that the officer establishes probable cause and it was not practical to secure a secure a search warrant because the vehicle and suspected contraband was mobile and would be gone before obtaining a search warrant and returning to serve the warrant (Supreme Court Landmarks, 2015).

katzKatz v. United States (1967) case was about the right to privacy and the Supreme Court of the United States decision refined previous court rulings on the interpretation of unreasonable search and seizure clause of the 4th Amendment to the U.S. Constitution (Supreme Court Landmarks, 2015). The Katz ruling also extended the protection of the 4th Amendment to the U.S. Constitution to all areas where a person has a reasonable expectation of privacy (Supreme Court Landmarks, 2015). The Katz ruling forced law enforcement to change their practices on searching without first articulating probable cause under oath and applying for a search warrant (Supreme Court Landmarks, 2015). For example, if an officer has to use a drone aircraft with a camera to look into a citizen’s backyard, this is not lawful because it was not in plain view and the person has an expectation of privacy. If any contraband were discovered, this would be an illegal search and the evidence not admissible in court because it was obtained illegally in violation of the 4th Amendment to the U.S. Constitution.

downloadIllinois v. Gates (1983) case established the “totality of the circumstances” test (Supreme Court Landmarks, 2015). The Supreme Court of the United States expanded how probable cause could be articulated and established by law enforcement officers that a crime was in progress, about to occur, or had already occurred (Supreme Court Landmarks, 2015). What the courts have said with this ruling is that if criminal intelligence is reliable and adding up and would cause a reasonable person to believe a crime is being committed and the police officers can articulate this based on their training, experience, and knowledge that all of this information coming together can establish probable cause.

jd-group-presentation-072611-6-728 (2)The Supreme Court of the United States ruled in the Brady v. Maryland (1963) case that the prosecutor office must turn over evidence that will be used at trial to the defense for examination (exculpatory evidence) or it violates the defendant’s due process of law a violation of the 14th Amendment of the United States Constitution (Supreme Court Landmarks, 2015). This could also include evidence that the investigator or police officer on the case have past violations of misconduct (Supreme Court Landmarks, 2015). This ruling created the “Brady Disclosure” to turn over exculpatory evidence (Supreme Court Landmarks, 2015).

downloadThe Tennessee v. Garner (1985) Supreme Court of the United States ruling changed police practices on using deadly force to shoot fleeing felons (Supreme Court Landmarks, 2015). The court ruled, under the 4th Amendment to the U.S. Constitution, that a law enforcement officer pursuing a fleeing suspect, cannot use deadly force to prevent the escapee unless the officer has probable cause the suspect poses an immediate threat of death or serious bodily harm to the officer or others (Supreme Court Landmarks, 2015). This ruling prevents officers shooting unarmed and non-threatening offenders who are fleeing.

Gv WThe Gideon v. Wainwright (1963) Supreme Court of the United States ruling ensures that a person charged with a felony has the right of counsel at trial, and by the state not providing the defendant legal representation is a violation of the 6th Amendment to the U.S. Constitution in a fundamental fair trial (Supreme Court Landmarks, 2015). The state’s failure to provide legal counsel for the accused violates the due process clause of the 14th Amendment to the U.S. Constitution (Supreme Court Landmarks, 2015). Some people in the criminal justice system call this the employment of the public defender act because every accused person has a right to legal representation even if they have no funds to pay for a lawyer, the court must provide one.

drugdog (2)Rodriguez v. United States (2015) the Supreme Court of the United States ruled that police officers cannot extend the length of a traffic stop for the purpose of searching a vehicle using a trained K-9 to alert to illegal contraband that is unrelated to the original purpose of the vehicle stop (Supreme Court Landmarks, 2015). Officers who make a lawful traffic stop for a traffic violation and issue the driver a ticket or even a warning cannot hold the driver awaiting for a K-9 officer and trained dog to arrive past the original traffic violating ticketing process if there is no probable cause that contraband is in the vehicle.

downloadIn the Maryland v. Wilson (1997) case, the Supreme Court of the United States extended the Pennsylvania v. Mimms (1997) ruling (Supreme Court Landmarks, 2015). The Maryland v. Wilson (1997) ruling extended to passengers in a vehicle as well as the driver must exit a lawfully stopped vehicle when the officer has probable cause that the occupants of the vehicle pose a threat to officer safety during the traffic stop (Supreme Court Landmarks, 2015). The ruling allows officer to exercise command of the situation for officer and vehicle occupant safety (Supreme Court Landmarks, 2015). This is not a search for contraband but a tool for officer safety. If contraband is then seen in plain-view in the vehicle after occupants are out of the vehicle this would be a lawful search and could lead to the arrest of the occupants.

download (1)In the Scott v. Harris (2007) case, the Supreme Court of the United States ruled that person fleeing from the police in a vehicle pursuit and the police use of force to stop the vehicle from harming others is not a violation of the defendant’s unreasonable seizure under the 4th Amendment to the U.S. Constitution (Supreme Court Landmarks, 2015). Justice Scalia stated, “The court rules that a police officer’s attempt to terminate a dangerous high-speed car chase that threatens the lives of innocent bystanders does not violate the Fourth Amendment, even when it places the fleeing motorist at risk of serious injury or death” (USC, 2015, p. 8).

mNew Jersey v. T. L. O. (1985) case was about the 4th Amendment to the U.S. Constitution rights against unreasonable searches (Supreme Court Landmarks, 2015). The Supreme Court of the United States ruled that a search on public school include searching personal items of students such as a backpack or purse for illegal contraband was reasonable and that this did not violate the 4th Amendment to the U.S. Constitution rights against unreasonable search clause when probable cause has already been established (Supreme Court Landmarks, 2015). School resources officer should beware of this ruling when searching on school grounds.

09BE7895-53AF-4164-9C20-92500D283654Georgia v. Randolph (2006) case involves the 4th Amendment to the U.S. Constitution and consent to search when one occupant agrees to the warrantless search and the other occupant refuses to allow a warrantless search of the property (Supreme Court Landmarks, 2015). The Supreme Court of the United States ruling strengthened the “co-occupant consent rule” in which both parties that are present on the scene must consent to the warrantless search for it to be lawful consent search and any contraband seized and used as admissible evidence (Supreme Court Landmarks, 2015).


Criminal law in the United States is constantly evolving with the protection of individual rights of the accused. The courts must weigh the evidence of the case and the specific actions taken to determine if the federal/state prosecutor and law enforcement officers are enforcing the laws and at the same time staying within the guidelines of the U.S. Constitution so that their actions are legal. Sometimes, even good intentions; however noble and honest, are in violation of the U.S. Constitution and the court rulings.

The Supreme Court of the United States rulings are final as the highest court in the land. The judicial decisions made by the Supreme Court of the United States establishes legal precedent and case-law for the lower courts (trial courts) and law enforcement to follow.

The landmark court cases discussed in this lesson are only but a few of the important cases decided upon by the Supreme Court of the United States that affects federal/state prosecutors and law enforcement officers. Progressing in your studies there will be additional opportunities to explore more court ruling that impact police practices. There are always cases in front of the Supreme Court of the United States that can affect future police policies, strategies, and tactics for enforcing the laws. Staying current on new court rulings is good citizenship and being informed makes us better criminal justice scholars.

Court rulings often cause law enforcement agencies to adopt new training and educational classes on what the court rulings mean to policing and how to stay compliant when interpreting new court rulings. Often the federal/state prosecutors will conduct training classes for law enforcement agencies on new court rulings to ensure compliance with the changes in the law.

A good law enforcement investigator establishes a good working relationship with the prosecutor’s office. Using the legal expert’s knowledge of the law will help you bring stronger criminal cases when violations of criminal law occur in your jurisdiction.


Facts and Case Summary – Miranda v. Arizona. (2015). United States Courts (USC). Retrieved from http://www.uscourts.gov/educational-resources/educational-activities/facts-and-case-summary-miranda-v-arizona

Supreme Court Landmarks. (2015). United States Courts (USC). Retrieved from http://www.uscourts.gov/about-federal-courts/educational-resources/supreme-court-landmarks

United States Courts (USC). (2015). Rules and policies. Retrieved from http://www.uscourts.gov/rules-policies

About the Author

Mark Bond

Mark Bond has worked in law enforcement and has been a firearms instructor for more than 33 years. His law enforcement experience includes the military, local, state and federal levels as a police officer and criminal investigator. Mark obtained a BS and MS in criminal justice, and M.Ed in educational leadership with Summa Cum Laude honors. As a lifelong learner, he is currently pursuing a doctoral degree in education (EdD) with a concentration in college teaching and learning. Mark is currently an assistant professor of criminal justice at a university and adjunct professor of administration of justice studies at a community college.