Buried for a Reason - What Copilot Shouldn't See

/ Owlegal GmbH/

How to keep outdated and sensitive content out of Copilot

A legal team's SharePoint typically contains far more information than Copilot should be processing. If Copilot encounters outdated versions, such as superseded drafts or policies, there is a risk that it will incorporate this content into its responses, undermining their reliability and quality.

As a general rule, Copilot can access anything I have access to. This includes confidential materials such as internal investigation files, my notes on litigation strategy or documents relating to a corporate transaction that has not yet been announced. There are compelling reasons to prevent Copilot from accessing sensitive content.

Some legal departments have already addressed these questions. For those that have yet to tackle them, or would like to review their existing approach, I have put together an overview of the available options.

Excluding Outdated Content

For outdated content that needs to be retained but no longer needs to be readily accessible, archiving solutions such as Microsoft 365 Archive are suitable. For documents that the team still needs to access occasionally, however, other solutions are required.

A superseded signing policy, replaced terms and conditions or last year's contract template should remain easy to find without competing with the current versions in Copilot's responses.

OPTION 1 · EXCLUDING CONTENT FROM SEARCH

One radical option is to exclude an entire library or site from SharePoint search. The content will then no longer be indexed. Copilot Chat and Copilot Search will no longer find it, but neither will SharePoint search, even within the library itself. Excluding content from search is therefore not a practical solution.

OPTION 2 · RESTRICTED CONTENT DISCOVERY

Restricted Content Discovery (RCD) offers a more nuanced approach. SharePoint Advanced Management, which is included with the Copilot licence, allows RCD to be enabled for a site. The site is then excluded from organisation-wide search and, consequently, from Copilot. Copilot in SharePoint is also unavailable on an RCD-enabled site.

Microsoft primarily positions RCD as a transitional solution when introducing Copilot. In practice, however, there is no time limit on its use. There is therefore no reason not to move archive libraries to an RCD-enabled site.

The documents continue to be indexed, and SharePoint search within the RCD-enabled site and its libraries continues to work as before.

Importantly, RCD applies to the site, not to individual documents. If I have copies of outdated documents stored in my OneDrive, Copilot can still access them without restriction. If I open content from an RCD-enabled site in Word, Excel or PowerPoint, I can work on it using Copilot, making it temporarily accessible to my Copilot again.

RCD is therefore not a completely reliable way to hide documents, but it offers many teams a pragmatic approach to keeping Copilot's responses up to date.

A CLOSER LOOK · METADATA

Some readers may now be wondering: Why do I need to block Copilot at all? Would it not be more useful to tell it which content is current and which is outdated?

Many legal teams maintain metadata columns in their SharePoint libraries for templates and policies, such as status fields or dates indicating when documents take effect or cease to apply.

Copilot in SharePoint can now read metadata and uses it fairly reliably. The situation is different with Copilot Chat, while Copilot Search still makes limited use of custom metadata columns.

For now, reliably excluding inactive documents still means making them inaccessible to Copilot.

Confidential Documents

OPTION 1 · RCD

If it is sufficient to store confidential documents somewhere Copilot cannot read them, an RCD-enabled site is an option, just as it is for outdated documents.

However, the protection depends on where the document is stored. If a document is sent by email, shared in a Teams chat or copied to OneDrive, Copilot can use that copy again. And if I open a document from the site in Word, I can still use Copilot to work on it.

For particularly sensitive documents, this is unsatisfactory. If I want Copilot protection that stays with the document itself, I need a different or additional safeguard. What are the options?

OPTION 2 · PASSWORD PROTECTION

Let us start with an old-fashioned method, one that feels like a relic from another era but which I still encounter occasionally: manually password-protecting a file.

A password encrypts the document, preventing Copilot from accessing its encrypted content.

However, once I open the document, the protection is effectively gone and Copilot can access its contents in full. This method is therefore not only outdated but also of limited effectiveness.

OPTION 3 · SENSITIVITY LABELS AND DLP

Microsoft Purview offers a more modern and effective way to control Copilot's access.

Purview allows organisations to configure a Data Loss Prevention (DLP) policy specifically for Microsoft 365 Copilot. Alongside existing sensitivity labels, a label such as "No Copilot" can be created. The corresponding DLP action, "Prevent Copilot from processing content", ensures that Copilot ignores the contents of documents carrying this label.

Once a document has been assigned this sensitivity label, the label stays with the file. Whether the document is copied to OneDrive, moved to another SharePoint site or stored locally, the protection remains active regardless of its location.

Copilot is also blocked from processing the file when it is opened directly in the desktop or web versions of Word, Excel or PowerPoint.

Unlike site-level RCD, this approach does not affect organisation-wide SharePoint search for human users.

Another particularly interesting feature for legal teams is the ability to apply the label to an entire SharePoint library, so that every new document saved there automatically receives the label.

There is, however, a catch: the DLP policy for Copilot is not included in every Microsoft licence. Microsoft specifies E5 or an additional Purview package. Given the many possible licensing combinations, it is worth checking the requirements with your licensing partner.

OPTION 4 · SENSITIVITY LABEL WITHOUT EXTRACT PERMISSION

Without the necessary Purview licence, an alternative is to use the permissions associated with a sensitivity label: users retain EDIT permission but are denied EXTRACT permission. However, this does not allow editing rights and Copilot access to be controlled entirely independently.

Copilot requires EXTRACT permission and is blocked without it. Users can still edit the file, at least in the Office desktop applications. However, they can no longer copy text out of the document, which can be inconvenient in everyday work.

If someone does have EXTRACT permission, for example because they created the file, Copilot can access the document on their behalf. Furthermore, the filename may still appear in Copilot Chat or Copilot Search.

Where Does This Leave Us?

If documents need to remain easy to find and edit while being hidden from Copilot, there is currently no silver bullet.

For outdated content that should nevertheless remain readily accessible, enabling RCD at site level is likely to offer most legal teams a pragmatic and acceptable solution for keeping content out of Copilot, even if the protection is not comprehensive.

For particularly confidential documents, the most promising approach is to effectively block Copilot through a combination of sensitivity labels and DLP policies, provided the necessary licences are available.

It is entirely possible that this article will already be outdated in six months' time. Until then, I would welcome an exchange of experiences: How do you keep Copilot away from your documents?

Géraldine Riethmann - OWLEGAL - October 2026