Nearly three-quarters of a century ago, the Supreme Court of the United States, expounding on the legal and ethical responsibilities of a prosecutor, announced that “while he may strike hard blows, he is not at liberty to strike foul ones. It is as much his duty to refrain from improper methods calculated to produce a wrongful conviction as it is to use every legitimate means to bring about a just one.” Berger v. United States, 295 U.S. 78, 88 (1935).
Wilkes, Donald E. Jr., "Still Striking Foul Blows" (2006). Popular Media. Paper 135.