In civil actions in federal court, either party may make a pre-trial motion for summary judgment. To succeed in a motion for summary judgment, a movant must show 1) that there are no disputed material issues of fact, and 2) that the movant is entitled to judgment as a matter of law.
When considering motions for summary judgment, judges view all evidence in the light most favorable to the movant's opponent. As used here, "material issues of fact" refers to any facts that could allow a fact-finder to decide against the movant. If the motion is granted, there will be no trial. The judge will immediately enter judgment for the movant.
Judges may grant partial summary judgment. For example, a judge might rule on some factual issues, but leave others for trial. Alternately, a judge might grant summary judgment regarding liability, but still hold a trial to determine damages.
When the court considers a motion for summary judgment, all parties involved may submit affidavits and other supporting evidence. In Celotex Corp. v. Catrett, 477 U.S. 317 (1986), the Supreme Court held that if one party advances factual support for their claims, and a second merely rests on its pleadings, the court may grant summary judgment against the second party.