The Seventh Amendment (Amendment VII) of the United States Constitution, which is part of the Bill of Rights, codifies the right to a jury trial in certain civil trials. Unlike most of the Bill of Rights, the Supreme Court has not incorporated the amendment's requirements to the states under the Fourteenth Amendment.
In Suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved, and no fact tried by a jury, shall be otherwise re-examined in any Court of the United States, than according to the rules of the common law.
In 1938, the Federal Rules of Civil Procedure merged the law and equity jurisdictions. Juries were to be used whenever the case would have gone to the common law branch of the judiciary had the distinction between the courts been preserved. Slight difficulties arose, however, in cases involving both equitable and legal claims. Previously, such an action would have been split between the equity and common law sides of the court. The new Federal Rules of Civil Procedure, however, precluded such a division of the case. It has been held by the Supreme Court that where both equity and law are involved, the jury must first decide the legal issues, followed by a determination of equitable issues by the judge. Otherwise, the judge's ruling on the equitable issues would have the effect of collateral estoppel—predetermining the jury's handling of the facts and thus limiting the right to a jury trial on the legal issues. Nonetheless, a litigant seeking legal relief is entitled to a jury trial in a civil case where the action is comparable to what would have been a "suit at common law" at the time the Bill of Rights was ratified.
Even where a legal, rather than an equitable, issue is controverted, the judge has a role in the determination of the verdict. The Supreme Court has held that judges may opine on the facts in dispute (provided that the jury actually determines the dispute), direct the jury to pay special attention to certain evidence and require the jury to answer certain questions relating to the case in addition to giving a verdict. If the judge deems the plaintiff's evidence insufficient, he may direct the jury to find in the defendant's favor. The jury may, however, return a verdict contrary to the judge's direction.
As common law provided, the judge could set aside (or nullify) a jury verdict that he deemed went contrary to the evidence or the law. Common law precluded the judge from himself entering a verdict; a new trial, with a new jury, was the only course permissible. In Slocum v. New York Insurance Co. (1913), the Supreme Court upheld this rule. Later cases have undermined Slocum, but generally only when the evidence is overwhelming, or if a specific law provides narrow guidelines by which there can be no reasonable question as to the required outcome, may the court enter "judgment as a matter of law" or otherwise set aside the jury's findings.