A more thorough explanation:

Definition: Test cases refer to legal actions brought with the intention of challenging or receiving clarification on a present law. The strategy usually involves creating a “controversy” to get into a court that otherwise would not lead to a legal action because courts must have an actual dispute to hear a case. Since the goal is to make a court rule on a particular issue, litigants must strategically choose the right case to bring with beneficial facts, location, and timing so that a court makes a ruling based on the issue brought by the litigants rather than on another issue.

Litigants use test cases to get a favorable ruling by all levels of courts, but the practice most popularly has been used to get a ruling by the Supreme Court on an important issue. For example, in the civil rights cases of the late 19th and 20th centuries, non-profit organizations, businesses, or the government itself used test cases to challenge discriminatory laws and practices. Many of the most well-known cases in the history of the Supreme Court are test cases such as Plessy v. Ferguson, Griswold v. Connecticut, and Brown v. Board of Education.

The strategy of using test cases must be done in a careful manner because the result of bringing the case could be the opposite of that intended. For example, in Korematsu v. U.S., the American Civil Liberties Union brought a test case to challenge the legality of the federal government’s detention of Japanese-Americans based on their race in the 1940s, but instead of overturning the law allowing detention, the Supreme Court affirmed the practice as a “military necessity.” These unintended outcomes of test cases can lead to long-term consequences that can be difficult to reverse in the future. Also, the outcome of the test case typically determines the outcome of many other cases waiting on the outcome, meaning the test case impacts much more than the litigants in the present case.

Example: A non-profit organization brings a test case to challenge a state law that requires voters to show a government-issued photo ID at the polls. The organization strategically chooses a plaintiff who is elderly and does not have a driver's license, making it difficult for them to obtain the required ID. The case is brought in a district court that has previously ruled against similar voter ID laws. The goal is to get a favorable ruling that will set a precedent for other states with similar laws. If successful, the ruling could make it easier for people without photo IDs to vote in future elections.

Explanation: This example illustrates how a test case can be used to challenge a law and set a precedent for future cases. The non-profit organization strategically chose a plaintiff with a compelling story that would make it difficult for them to obtain the required ID. By bringing the case in a district court that has previously ruled against similar laws, the organization increases the chances of a favorable ruling. If successful, the ruling could impact other states with similar laws and make it easier for people without photo IDs to vote in future elections.