Electronically stored information (ESI)
Electronically stored information (ESI) is the term used in Rule 34 of the Federal Rules of Civil Procedure for information stored in any electronic medium from which it can be obtained: email, documents, spreadsheets, databases, chat and collaboration data, mobile device content, audio and video, social media and metadata. It is the subject matter of eDiscovery.
Also called: ESI · ESI documents · electronic evidence
Updated September 6, 2026
What counts as ESI under the Federal Rules?
The 2006 amendments to the Federal Rules of Civil Procedure added “electronically stored information” alongside “documents” to make explicit that electronic data is discoverable in its own right, with its own rules on form of production, accessibility and preservation. Most state rules have since followed.
Three things distinguish ESI from paper. It carries metadata (dates, authors, edit histories) that may itself be evidence. It exists in volume paper never reached, so culling and deduplication are necessary rather than optional. And it can be altered or destroyed by routine system processes, which is why a litigation hold must suspend automatic deletion.
What does ESI look like in practice?
For one custodian in a commercial dispute, the ESI in play might be: a mailbox and its archive, a home directory on a file share, a OneDrive, Teams channels and chats, text messages on a company phone, calendar entries, and rows in a CRM. Each source has a different collection method, a different volume profile and a different production form, which is what the ESI protocol exists to settle.
How does ESI show up on an eDiscovery invoice?
ESI volume is what most eDiscovery pricing meters. Collection is priced per source or per hour; processing per gigabyte ingested; hosting per gigabyte per month for the life of the matter. Because the same gigabyte can hold 15,000 pages of scans or 100,000 pages of email, per-gigabyte pricing tracks storage rather than work. See the volume translator.
Sources
- Fed. R. Civ. P. 34(a)(1)(A) and the 2006 Advisory Committee Notes.
- Fed. R. Civ. P. 26(b)(2)(B) on ESI that is not reasonably accessible.
- The Sedona Conference Glossary, “electronically stored information.”
Related terms
ESI protocol · Custodian · Metadata · Litigation hold · Collection
eDiscovery at one flat monthly rate
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Common questions
What does ESI mean in litigation?
It means information in electronic form that a party may have to preserve, search and produce. Rule 34(a)(1)(A) covers writings, drawings, graphs, charts, photographs, sound recordings, images and other data or data compilations stored in any medium. In practice it is nearly everything a business creates.
What are ESI documents?
Any electronic file that could be responsive: an email and its attachments, a Word document with its revision history, a spreadsheet with its formulas, a Slack channel, a text message thread, a database record, a voicemail. Each has its own metadata and its own production challenges.
Is ESI the same as an ESI injection?
No. In medicine ESI means epidural steroid injection. In litigation it means electronically stored information. The two share nothing but the abbreviation, which is why search results for the bare term are unreliable.