Formal Discovery: Gathering Evidence for Your Lawsuit

Learn about formal discovery in a lawsuit using the most common discovery techniques.

By , UCLA Law School Professor
Updated 5/17/2024

Discovery in law is a process used to seek information needed to prove claims in a lawsuit. Discovery begins soon after a lawsuit gets underway, with the parties to the lawsuit or their lawyers gathering needed information from the opposing side and potential witnesses. The process is called "discovery" because it often reveals facts and documents previously unknown to at least one party to the lawsuit.

Gathering Evidence Using Formal Discovery

Most discovery occurs outside the courtroom, with parties exchanging written information and sitting through face-to-face questioning sessions (called "depositions"). The types of evidence that can be legally obtained are very broad, including:

  • facts about the case
  • the identity of others who might know something about the case
  • documents relating to the case, and
  • inspection of physical objects or property connected to the dispute.

How to Do Discovery in a Lawsuit: Discovery Procedures

Four types of formal discovery tools are frequently used in lawsuits. The most common discovery techniques include:

  • Depositions. In a deposition, one party or that party's lawyer conducts face-to-face questioning of the other party or a witness to the dispute. The person being questioned (the "deponent") must answer under oath, and the answers are recorded for later use at trial. If the deponent cannot testify at trial, the questions and answers might be read to the jury as evidence. If the deponent does testify and gives different answers at trial from those he gave during the deposition, the questions and answers can be used to show the jury that the witness changed his story.
  • Requests for production of evidence. In a request for the production of evidence, one party asks the other for physical evidence related to the dispute. Requests for production are usually used to gather pertinent documents, such as contracts, employment files, billing records, or documents related to real estate. However, these requests can also be used to inspect physical objects or property -- for example, in a dispute about whether a contractor properly repaired a homeowner's roof, the contractor's lawyer might ask to have a roofing expert inspect the work.
  • Interrogatories. Interrogatories are written questions one party sends to the other to be answered under oath. The answers can be used at trial in the same way as deposition answers -- to challenge a party who changes her story later.
  • Requests for admission. In a request for admission, one party asks the other party to admit, under oath, that certain facts are true or certain documents are genuine. These requests are generally used to save time and narrow the issues that must be proved at trial.

Examples of Discovery in Law: What Can Be Discovered

The basic rule of discovery is that a party may obtain any information that pertains even slightly to any issue in the lawsuit as long as the information is not "privileged" or otherwise legally protected (see "Discovery Limits" below). Here are some of the things lawyers often ask for in discovery:

  • anything a witness or party saw, heard, or did in connection with the dispute
  • anything anyone said at a particular time and place (for example, in a business meeting related to the dispute or after a car accident that turned into a lawsuit)
  • the identity of anyone who might know something about the dispute or about the injuries or money losses either party suffered
  • detailed information on how a business is run (for example, a party might try to determine how a company that sold a dangerous product decides what to sell or how a business makes employment-related decisions or keeps its accounting records)
  • documents relating to the dispute, and
  • the personal, educational, and professional background of a witness.

Limits on What Can Be Discovered

Virtually any information that might be slightly connected to the lawsuit is fair game for discovery. But this enormous latitude sometimes leads to abuse. Lawyers might try to pry into subjects with no legitimate significance for the lawsuit or are private and confidential, only to annoy or embarrass the parties. Fortunately, there are some legal limits on this kind of probing and some protections to keep private material from being disclosed to the public.

Confidential conversations. Conversations between people engaged in certain relationships are given a special legal protection known as privilege. Courts and legislatures have decided that the free flow of confidential information in these relationships is so important that it must be protected, even though that information might be important to others in a lawsuit. Under the law, no one can be required to disclose any information, whether verbal or written, that was confidentially exchanged within the following relationships:

  • husband and wife
  • lawyer and client
  • doctor and patient, and
  • religious advisor and advisee (although this privilege is often referred to as "priest-penitent," it applies more generally to any confidential conversation between a clergy member of a recognized religion and a person seeking spiritual counsel).

Private matters. In recent years, courts have increasingly recognized that some aspects of personal life should remain private, beyond the reach even of lawyers. But the right to privacy is a fairly recent and still-developing legal notion. As a result, there is no clear definition of precisely what it covers -- and the extent of its protection varies considerably from state to state. Roughly, the right to privacy protects a person from having to divulge information that is not obviously relevant to the lawsuit and is a matter that a person would not normally discuss or reveal to anyone outside of immediate family and intimate friends. This might include issues such as:

  • health or body issues
  • sexuality, sexual practices, or sexual partners
  • spiritual or religious beliefs, and
  • immediate family relationships.

Privacy rights of third parties. Courts are more willing to protect the privacy of third parties -- for example, witnesses, co-workers, or family members of a party -- than the privacy of parties to a lawsuit. Courts often limit how much a party can find out about someone who isn't involved in a lawsuit, reasoning that it isn't fair to invade the privacy of someone who was dragged into a dispute.

Keeping discovery information from the public. Even if a party is required to disclose certain information to the other side in a lawsuit, that information can be treated confidentially by the court -- that is, the party who receives it can be prevented from revealing it to anyone else, and the court can keep it out of the public record. This might be done to protect, for example, sensitive financial information, confidential information belonging to a business, or personal medication information that is relevant to the lawsuit. For this to happen, a judge must usually order that information be kept confidential, in what's often called a "protective order."

Want to Learn More?

These discovery tools are explained in detail in Represent Yourself in Court, by Paul Bergman and Sara Berman (Nolo), and Nolo's Deposition Handbook, by Paul Bergman and Albert Moore.