In a civil lawsuit, an attorney representing a defendant has several requests he can make to a judge to attempt to dismiss a case filed against his client. One such tool is a motion for summary judgment.
For a defendant to prevail on a motion for summary judgment, he must show there is no genuine issue of material fact the plaintiff is entitled to prevail upon in the lawsuit; the evidence put forth by the plaintiff does not support a verdict in his favor.
In federal court, a motion for summary judgment is governed by Federal Rule of Civil Procedure 56. In state court, the rule is generally the same but may be a different rule number. This rule dictates when the motion can be filed and what the defendant must prove to prevail on the motion.
An unopposed motion in the law is one where the other party or parties to the lawsuit do not fight against or counter your request. Here, a judge would not receive any opposition from the plaintiff after the defendant files a motion for summary judgment, leaving the judge little reason not to grant the defendant's motion.