In plain English
A legal hold freezes specific data in place — even if normal retention policies would delete it — to ensure it's available for legal proceedings. In Microsoft Purview, a legal hold can be applied to a specific user's mailbox and SharePoint content, preserving everything they send, receive, and save for the duration of the matter.
Full definition
When litigation is on the horizon, normal data management stops. Scheduled deletions pause. Retention policies that would ordinarily purge old emails no longer apply. Everything relevant to the matter gets frozen in place until a court or legal team says otherwise.
A legal hold is that instruction, documented and applied to specific custodians or content sources. In , a legal hold can be placed on an individual mailbox, a site, or a Teams channel. Everything within scope is preserved regardless of what the user does afterwards, including content the user deletes from their own view. The hold is invisible to the person it applies to.
Failing to act on a legal hold obligation carries real consequences in Australian civil litigation. If a party cannot produce documents that should have been preserved, courts can draw adverse inferences about why those records are missing. For organisations under a regulatory investigation, the obligation to preserve relevant data can arise before any formal legal proceeding begins. Legal teams and IT administrators need a clear process for receiving hold instructions, identifying the right custodians, applying the hold in the relevant systems, and confirming it is working. An informal email chain is not a defensible record of that process.