In the 1912 case of Lem Woon v. State of Oregon, Chinese immigrant Lem Woon was convicted for the murder of Lew Moy in Portland, Oregon. The Supreme Court reviewed his appeal based on two main points: that he had been denied a fair trial due to racial prejudice and that there were errors made during jury instructions regarding reasonable doubt. However, the court rejected both arguments and upheld his conviction. Woon argued that because he was not allowed an interpreter during grand jury proceedings, this violated his rights under federal law which provided interpreters for those who could not understand English well enough to participate fully in their defense. He also claimed bias from jurors who held prejudiced views against Chinese immigrants. The Supreme Court ruled against him on both counts; they found no evidence of juror bias or misconduct and stated it wasn't necessary for an interpreter to be present at grand jury proceedings as long as one was available at trial itself where guilt or innocence is determined. Regarding reasonable doubt instruction given by judge to jurors, while acknowledging some potential confusion caused by wording used about presumption of innocence being "not intended to aid anyone who is in fact guilty", they concluded it did not mislead jurors into thinking burden proof shifted onto defendant.

In the dissenting opinion for Lem Woon v. State of Oregon, it was argued that the defendant's constitutional rights were violated due to lack of proper legal representation during his trial. The justice emphasized that every individual has a right to counsel and this is fundamental in ensuring fair trials. In this case, however, Lem Woon did not have an attorney present when he pleaded guilty to murder charges which led him being sentenced to death by hanging. The justice believed that if Woon had been given adequate legal advice at the time of entering his plea, he might not have pleaded guilty or could have presented mitigating circumstances affecting sentencing decisions. Therefore, according to the dissenting opinion, there was a failure in providing equal protection under law as required by Fourteenth Amendment and thus called for reversal of judgment.