Bonner v. United States was a United States Supreme Court case that dealt with the issue of whether a defendant could be convicted of a crime if the indictment was not found by a grand jury. The case involved a man named William Bonner, who was charged with the crime of counterfeiting. Bonner argued that he could not be convicted of the crime because the indictment was not found by a grand jury. The Supreme Court disagreed and held that a defendant could be convicted of a crime even if the indictment was not found by a grand jury. The Court reasoned that the Fifth Amendment did not require a grand jury to find an indictment in order for a defendant to be convicted of a crime. The Court also noted that the Sixth Amendment did not require a grand jury to find an indictment in order for a defendant to be convicted of a crime. The Court concluded that a defendant could be convicted of a crime even if the indictment was not found by a grand jury. This ruling established that a defendant could be convicted of a crime without a grand jury finding an indictment.

In Bonner v. United States, the Supreme Court was tasked with determining whether a defendant could be convicted of an offense not specified in the indictment against them. The majority opinion held that such convictions were permissible under certain circumstances, while Justice Field dissented from this ruling. He argued that allowing defendants to be convicted of offenses not charged in their indictments would violate due process and deprive them of their right to notice as guaranteed by the Fifth Amendment's Grand Jury Clause. Furthermore, he noted that it is essential for criminal proceedings to adhere strictly to statutory requirements so as not to undermine public confidence in judicial decisions or create uncertainty about what constitutes a crime and its punishment. As such, Justice Field concluded that any conviction must rest upon charges made known at trial or else risk violating fundamental principles of justice and fairness enshrined within our Constitution.