The U.S. Supreme Court has never ruled that official English legislation is unconstitutional.

Arizonans for Official English v. Arizona was expected to be the test case for official English laws. Arizona state employee Maria-Kelley Yniguez filed the lawsuit in 1988, challenging Arizona’s official English law. The federal district court in Arizona ruled that the official English law was "facially overbroad." This meant that the law was so broad that it violated the First Amendment. The Court of Appeals for the Ninth Circuit agreed. The case was appealed to the U.S. Supreme Court.

However, the Supreme Court did not decide the case on the merits. Instead, they unanimously vacated the decision of the Ninth Circuit and sent the case back to the district court with instructions to dismiss. The justices ruled that the case was moot because Ms. Yniguez voluntarily left her employment with the state of Arizona. Justice Ginsburg’s opinion specifically did not rule on the constitutionality of official English legislation. Instead, it said the lower federal courts should have allowed the state courts a chance to interpret their own state’s law.

The second possible test case was Ruiz v. Hull. The Arizona state trial court ruled that the official English law did not violate the Constitution. The Arizona court of appeals did not interpret the law itself, but in order to prevent confusion it deferred to the interpretation of the federal courts and ruled the law unconstitutional.

The Arizona Supreme Court struck down the official language amendment to the state constitution in April 1998. However, the court pointed to more narrowly crafted official English laws such as those in Montana and Wyoming, saying that if Arizona's law had contained similar exceptions, "it might well have passed constitutional muster." The U.S. Supreme Court denied an appeal in the case, so the Arizona State Supreme Court decision is final.

Since the denial of appeal has no precedential value, there is no U.S. Supreme Court precedent against official English laws.

In analyzing the constitutionality of official English legislation, note that the Arizona Supreme Court ruling and the (no longer valid) federal rulings were based on the concept of "overbreadth." The courts did not say that official English laws are always unconstitutional—merely that Arizona’s particular law was overly broad. A more narrowly drawn law could avoid such a challenge and be constitutional.

There is no legal precedent for the proposition that official English laws are unconstitutional per se. Carefully drafted, specific legislation making English the official language of government, with reasonable exceptions, will most likely be constitutional.