Langford v. United States was a case heard by the United States Supreme Court in 1879. The case involved a dispute between the United States and a man named William Langford, who had been convicted of a crime in the state of Georgia. Langford argued that the conviction was invalid because the jury that convicted him was not properly selected. The Supreme Court ruled in favor of Langford, finding that the jury selection process used by the state of Georgia was unconstitutional. The Court held that the jury selection process violated the Sixth Amendment of the United States Constitution, which guarantees the right to a trial by an impartial jury. The Court also held that the state of Georgia had violated the Fourteenth Amendment, which guarantees due process of law. The Court's ruling in Langford v. United States established an important precedent for jury selection in the United States. The ruling established that jury selection must be conducted in a manner that is fair and impartial, and that any violation of the Constitution in the selection process will invalidate the conviction.

Justice Field delivered the dissenting opinion in Langford v. United States, arguing that the majority's decision was wrongfully decided and should be reversed. He argued that Congress had no authority to pass a law which allowed for an appeal from a criminal conviction by way of habeas corpus when there was already an existing statute providing for such appeals. According to Justice Field, this new law violated both the letter and spirit of Article III of the Constitution, which grants exclusive jurisdiction over all cases arising under federal laws to courts established by Congress. Furthermore, he argued that allowing appeals through habeas corpus would create confusion among litigants as they would not know whether their case could be appealed or not depending on what court it originated in. Finally, Justice Field concluded his dissent by stating that if Congress wanted to provide additional avenues for appealing convictions then it should do so explicitly rather than relying on implied powers granted through statutes like those at issue here.