In Bruno v. United States (1939), the Supreme Court ruled that a defendant's right to be present at their own trial is not absolute, and can be waived if they voluntarily choose not to attend. The case involved two defendants, Bruno and another man, who were on trial for conspiracy to violate Prohibition laws. They chose not to attend their own trial despite being informed of their right to do so by the judge. After being convicted in absentia, they appealed on the grounds that their absence violated their Sixth Amendment rights. The Supreme Court disagreed with this argument, stating that while defendants have a constitutional right under the Sixth Amendment "to be confronted with witnesses against him," this does not mean they are required or obligated to exercise it; rather it is an option available for them should they wish it. Therefore, since both men had knowingly chosen not to exercise this right after having been duly informed about its existence and implications by the court officials handling their case originally - including potential consequences like conviction in absentia - there was no violation of any kind.

In the dissenting opinion for Bruno v. United States, Justice Black argued that the majority's decision violated the defendant's Sixth Amendment right to a fair trial by an impartial jury. He contended that allowing jurors to separate during recesses in a criminal trial could expose them to outside influences and prejudices, thereby undermining their ability to render an unbiased verdict based on evidence presented in court alone. Further, he disagreed with the majority’s reliance on common law practices from centuries ago when circumstances were vastly different than today’s modern society where communication is instant and widespread. Moreover, he believed it was not enough for courts merely trust jurors' oaths of impartiality without taking further precautions against potential bias or influence. Therefore, Justice Black concluded that any deviation from continuous sequestration of juries in criminal trials should be considered as prejudicial error unless proven otherwise.