A motion for discovery is a legal request to the court in a civil trial. The request asks the court to mandate that the opposing council and party turn over a given piece of material or information. It occurs during the pre-trial process in which each party prepares his or her case to present to the judge.

In the United States, when civil lawsuits are filed, each party is entitled to request certain evidence from the other side. This rule is in place because courts believe that often the person best capable of providing the evidence is the one being sued. For example, if an individual sues a company for fraud, it is most likely that the company will have documents that show the fraud occurred; as such, the plaintiff should be entitled access to those documents so he can prove the fraud he says exists does in fact exist.

As such, each party can file a discovery request of the opposing side. These requests must be tailored to the case at hand. In other words, any requests the party makes of the opposing side for information must be because he believes the request is likely to turn over something that can help him prove his case. When he files a motion for discovery requesting the court to compel the opposing side to turn over the information, he generally must specify what he is hoping to find within the documents or evidence and why he believes that evidence will be found.

A motion for discovery must also be reasonable. This means it must be narrowly tailored to the case and cannot be cost prohibitive. A plaintiff trying to prove fraud, for example, could request bank statements from a company during the period in which the alleged fraud occurred. He could not, however, request every financial document or email the company ever sent, as producing such information would likely be very costly for the company and would be unreasonable.

When a party makes a motion for discovery, the judge will consider the motion in light of the reasonableness and in light of the other party's opposing motions or requests, if any. Certain exceptions to discovery do exist, however. For example, privileged communication between clients and attorneys is not discoverable, and any request or motion for discovery of such information will generally be denied by a judge.