In the case of Edmund G. Brown, Jr., Governor of California, et al., v. Marciano Plata et al., 2010, the U.S Supreme Court ruled that California's prisons were so overcrowded they violated the Eighth Amendment’s prohibition on cruel and unusual punishment. The court ordered California to reduce its prison population by approximately 40,000 inmates within two years because it found that severe overcrowding was preventing prisoners from receiving adequate medical and mental health care. This decision upheld a lower court ruling which had also determined that reducing prison population was necessary to remedy constitutional violations in healthcare delivery. The state argued against this order claiming it would lead to dangerous criminals being released into society but failed to convince a majority of justices who voted 5-4 in favor of upholding the prisoner release order.

In the dissenting opinion for Edmund G. Brown, Jr., Governor of California, et al., v. Marciano Plata et al., Justice Scalia, joined by Justice Thomas, argued that the court order to reduce prison population in California was a drastic and unprecedented intrusion into state sovereignty. He contended that the Constitution does not give federal courts power to impose such an order on states unless it is proven beyond doubt that no other remedy could rectify constitutional violations within prisons. Furthermore, he expressed concern over potential public safety risks due to early release of prisoners and criticized majority's reliance on a panel of three judges rather than trial proceedings with cross-examination and rules of evidence applied strictly. Additionally, he disagreed with majority’s interpretation of Prison Litigation Reform Act (PLRA), arguing it should limit judicial authority instead of expanding it as interpreted by majority justices.