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Q53: How many justices are on the Supreme Court? 

A. Seven (7) 
B. Eight (8) 
C. Nine (9)
D. Ten (10)

Q54: How many Supreme Court justices are usually needed to decide a case? 

A. One, the Chief Justice  
B. Five (5) 
C. Six (6)
D. A unanimous vote

Question Background Information


The Constitution does not fix the number of justices on the Supreme Court beyond creating a Chief Justice position. There were initially six justices, but the number of justices changed throughout the 19th century, as more justices were added to supervise the expanding geographic scope of the nation, though occasionally, and very controversially, the number was reduced for political reasons as well. The Federalists reduced the number of justices to try to block Thomas Jefferson from being able to make a nomination, while Republicans wanted to keep the anti-Reconstruction president Andrew Johnson from appointing any.

Since 1869, the number of justices has been fixed at nine (9) justices. In the 1930s, Franklin Roosevelt attempted to add more justices in order to get more friendly rulings from the Supreme Court, but even many of his allies rejected this as an illegitimate violation of judicial independence, and the number remained at nine and still is to this day.

A majority of Supreme Court justices are required to decide a case, which normally means five (5) justices are necessary to issue a ruling.

There are several different types of opinions justices can write. Normally, a majority of the Court will deliver the “opinion of the Court”, which means it explains both the result of the case and the reasoning shared by any justices who sign it. Such opinions are binding precedent for lower courts.

Individual justices can also write concurring opinions, in which they agree with the opinion of the Court but have additional thoughts—perhaps disagreeing with the dissents, or suggesting how the Court may extend its logic in a future case. Sometimes judges will agree with the outcome of the case but disagree with the legal reasoning given in the opinion of the Court; in this case, they will write a “special concurrence” agreeing with the judgement – the what –  but not the reasoning – the why. Finally, justices who think the majority of the Court got the outcome wrong may write a dissent, explaining why, in the hopes a future court will overrule the opinion.

Additional Content

Offline Activity


It’s not easy to make decisions sometimes, and for those in positions of power -- such as a Supreme Court justice -- making a decision takes on an added weight. In this activity, students will have the chance to reflect on the challenges that can come with reviewing a law and determining its constitutionality by looking at excerpts of a case that the Court decided by 5-4. (That it was also a case with unusual alignments—with for example, Scalia, Thomas and Ginsburg in the majority—makes it more interesting.) After reading and annotating the case they will then have the chance to engage in a class discussion to argue their points of view.


  • Provide each student/group with the instruction sheet. 
  • Provide each student/group with Kyllo v. United States (2001)
  • A rubric is available if this is a graded activity.

Required files coming soon.

The Teaching Materials for this exercise includes a rubric.

Teaching Materials.


  1. Journaling is a solitary activity. However, depending on the age and/or skill level of the students, you may want to have them work in pairs.
    • If that is the case, divide the class into pairs based on the students’ individual levels. Group A is the group that needs some extra support. Group B is the core group that has the core knowledge to complete the activity. Group C is the enrichment group that has mastered the material. Group C students are prepared to extend their knowledge. Pair those who need support (Group A) with those who have core knowledge and/or have mastered the material (Groups B and C).
  2. Explain to the students that they are going to pretend they are a Supreme Court justice and have to reflect on whether to affirm or overrule a case that was previously decided 5-4, with a bare majority. It is their job to determine whether or not the court ruled correctly according to the Constitution.
    • To do this, they will write a journal entry where they state their opinion and provide their reasoning.
  3. Provide the students with the necessary materials.
  4. Make sure the students know that, because this is a journal, there are no perfectly “right” answers. The purpose of this activity is to help them engage in critical thinking and look at an issue from various points of view.
    • They should determine their stance: the Court ruled correctly or incorrectly in blocking the search with the thermal scanner.
    • They should be able to explain why they believe this and use the 4th Amendment and reasoning in the judicial opinions to support it.
    • They may also discuss their personal opinions, which may or may not be in line with their legal reasoning and ultimate answer.
      • For example, someone may be personally opposed to alcohol, and support its ban by a state, but realize that the regulation of the possession of alcohol is not granted to the federal government. Or, in this case they may support the punishment of drug manufacture but think this search illegal, or alternatively, they may oppose the criminalization of marijuana but think this search legal”…
  5. Circulate throughout the room to help students as needed.
  6. Once everyone is finished, lead a class discussion on the case and why the students ruled as they did. Be sure to cover the following points:
    • Why did you decide the search was constitutional? Why was it unconstitutional?
    • Do you personally agree with the decision? That is, did your legal reasoning match your personal views about the policy?

Discussion Prompts

Below are two discussion prompts that can be used by teachers in a classroom setting. 

  • The first discussion prompt will be one that is designed to support students that are not really understanding the content in a way that would help them to answer the test question.
  • The second discussion prompt will be one that is designed to further student understanding of the content by making real-world connections, including connections to current events and historical events.


The current number of nine justices is traditional, although there has evolved a strong norm that the number should only change for logistical or “good government” reasons (such as needing more justices to supervise new circuits), not to secure judicial outcomes. History has shown us that the Court can function with more -- and with fewer – justices, though of course this also involves changes in the number of cases they can or must hear, as well as their clerk staffing. 

Prompt 1

The original Supreme Court had six justices. The number has fluctuated over time. Sometimes, it has been as low as five; other times, it has been as high as ten. How many justices are there? How many does it take to decide a case? How is an odd number beneficial to decision-making? 

Prompt 2

Some states require a supermajority of state supreme court justices to rule a state law unconstitutional. They argue that there should be a higher standard in declaring unconstitutional laws passed by the people’s elected representatives. Most state constitution- writers have held that could make it too hard to enforce their state constitution, and use a majority system like the U.S. Supreme Court. Which do you think is a better system? Why do you feel this way? Use current and past events to support your answer.