A more thorough explanation:

Baker v. Carr (1962) is a landmark case in the United States that dealt with the issue of redistricting and the Equal Protection Clause of the Fourteenth Amendment of the Constitution. The case established that federal courts could hear cases alleging that a state's drawing of electoral boundaries violates the Equal Protection Clause. This means that if a state's redistricting plan unfairly favors one group of voters over another, it can be challenged in court.

For example, in the Baker v. Carr case, the plaintiff lived in an urban Tennessee voting district that was underrepresented compared to rural voting districts. Tennessee law required districts to be redrawn every ten years, but Tennessee had not done so in decades. The plaintiff sued in federal district court, claiming that the law required Tennessee to redraw their districts to make each district's representation substantially equal to its population.

The lower court held that the issue was a political question and therefore non-justiciable, dismissing the plaintiff's case. However, the U.S. Supreme Court disagreed and held that the constitutionality of a legislative appointment scheme was not a political question and therefore was justiciable. This means that a federal court could hear the case and decide on the merits.

In finding this case justiciable, the Court created the political question doctrine, which creates a series of factors that determine whether a case is non-justiciable. If any of the factors are met, then the court may not hear the case. For example, if the issue has already been decided by another branch of government, or if there are no standards for resolving the issue, the court may not hear the case.

By holding that such cases were justiciable, the Supreme Court paved the way for federal courts to hear and decide on claims that electoral districts violated the equal protection clause. Two years later, the U.S. Supreme Court relied on Baker to require that the United States House of Representatives and state legislatures establish electoral districts of equal population in Wesberry v. Sanders and Reynolds v. Sims.

Overall, Baker v. Carr was an important case that helped to establish the principle of equal representation in the United States. It ensured that all voters have an equal say in the political process, regardless of where they live or what their background is.