Discovery is a process by which the parties to a civil proceeding or matter are permitted to obtain, within certain defined limits, full information as to the existence and the contents of all relevant documents relating to the matters in question between them.

In any action begun by writ in the High Court and District Court, each party must (unless otherwise agreed or ordered), within 14 days after close of pleadings, disclose to each other all relevant documents (including those that are privileged or otherwise protected from inspection) that are or have been in their possession, custody or power by setting them out in a list of documents, which includes a brief description of the document. Once the lists of documents have been exchanged, the parties are entitled to inspect the documents referred to in the list, other than those privileged or protected from inspection, and to take copies of them.

This early exchange of information is intended to prevent trial by ambush, facilitate thorough trial preparation and an early assessment of the strengths and weaknesses of the parties' respective cases, and encourage settlement.

Only documents relating to matters in question are required to be disclosed. This includes documents that would tend to prove or disprove a matter in issue as well as documents which it is reasonable to suppose might enable the other party either to advance its own case or to damage the case of its adversary, or which might fairly lead to a train of inquiry that might have either of those two consequences.

Relevance is generally tested by reference to the pleadings and further particulars provided, but may extend to matters which, in the ordinary way, may be expected to be raised in the course of the proceedings. However, discovery will not be ordered in respect of an irrelevant allegation in the pleadings, which, even if substantiated, could not affect the result of the action, nor in respect of an allegation not made in the pleadings or particulars. Discovery will also not be allowed to enable a party to "fish" for witnesses or for grounds upon which to found their case. Nor will discovery be ordered in respect of documents leading an applicant to a train of inquiry that would only lead to matters not admissible in evidence.

Each case must be considered according to the issues raised. Where there are numerous documents of slight relevance, and it would be oppressive to produce all of them, some limitation may be imposed by the courts. Courts are empowered to, and will, by way of case management, limit the scope of automatic discovery that the parties would otherwise be required to make.

Where a party fails to make discovery or makes inadequate discovery, another party can apply to the court for an order for "general discovery." Where a party is dissatisfied with the list of documents from their opponent, further disclosure may also be obtained by applying for a further and better list (either in general terms or limited to certain classes of documents), or applying for an order of specific discovery of documents.