In United States v. Jung Ah Lung, the United States Supreme Court considered the question of whether a Chinese immigrant was subject to deportation under the Chinese Exclusion Act of 1882. The Court held that the Act applied to all Chinese immigrants, regardless of their status as a laborer or merchant. The case involved Jung Ah Lung, a Chinese immigrant who had been living in the United States for several years. He had been admitted to the United States as a merchant, but the government argued that he was actually a laborer and thus subject to deportation under the Chinese Exclusion Act. The Court held that the Act applied to all Chinese immigrants, regardless of their status as a laborer or merchant. The Court reasoned that the Act was intended to exclude all Chinese immigrants, and that the distinction between laborers and merchants was not relevant. The Court also noted that the Act was intended to protect American labor from competition from Chinese immigrants, and that the distinction between laborers and merchants was not necessary to achieve this goal. The Court's decision in United States v. Jung Ah Lung established that the Chinese Exclusion Act applied to all Chinese immigrants, regardless of their status as a laborer or merchant. The decision was an important step in the development of immigration law in the United States.

Justice Field delivered the dissenting opinion in United States v. Jung Ah Lung, arguing that the majority's decision was contrary to both precedent and common sense. He argued that Congress had not intended for Chinese immigrants who were already living in the United States when it passed its 1882 Exclusion Act to be subject to deportation under this law. Instead, he argued that they should have been allowed to remain as long as they did not leave and re-enter without permission or violate any other laws of their residence country. Furthermore, Justice Field noted that if these individuals were deported then there would be no way for them to return legally since all immigration from China had been suspended by Congress at this time. As such, he concluded that deporting these individuals would amount to a cruel punishment which was never intended by Congress when passing its exclusion act and thus should not be enforced against those already residing within US borders at the time of passage