When should organisations use information barriers to restrict communication between user groups?

Organisations should use information barriers when regulatory obligations, due diligence, or conflict-of-interest concerns require two groups to remain separated. The control is appropriate when email communication itself creates risk, not just when message content is sensitive. It helps prevent unauthorized sharing, supports compliance, and reduces the chance that internal communications become a data-loss path.

When information barriers are the right control

Information barriers make sense when the organisation needs to prevent communication between defined user groups, not merely protect the content of individual messages. They are most useful where legal, regulatory, ethical, or conflict-of-interest obligations require separation, and where ordinary content filtering would be too narrow because the communication channel itself creates the exposure.

The practical test is whether the risk comes from the act of two groups exchanging information at all. If the answer is yes, an information barrier is a better fit than ad hoc mailbox rules or manual monitoring, because it enforces separation at the boundary rather than trying to police every message after the fact.

That is why the control is often used in advisory, legal, finance, mergers and acquisitions, research, and other contexts where people on one side of a barrier should not be able to influence, receive from, or coordinate with the other side during a defined period or engagement.

How the control works in practice

An effective barrier is usually built as an access and communication policy, not as a single email rule. It needs clear group definitions, approved exceptions, logging, and a governance owner who can decide when the barrier starts, ends, or changes. The barrier should also be tested against the real communication paths people use, including mail, chat, collaboration platforms, shared calendars, and distribution lists.

Where the barrier is only partially implemented, users may still move information through indirect channels, such as forwarding, shared workspaces, or copied recipients. That means the control has to be aligned with the actual workflow, not just the stated policy. The objective is to reduce cross-group exchange to an acceptable and auditable level, not to assume that policy language alone will stop leakage.

For organisations that need a governance anchor for broader access control decisions, ISO/IEC 27001:2022 Information Security Management and ISO/IEC 27002:2022 Information Security Controls both support the idea that separation, access restriction, and control selection should follow business need and documented governance.

When communication separation is part of a broader compliance or access-control programme, organisations often map it to formal control families such as NIST SP 800-53 Rev 5 Security and Privacy Controls and NIST Cybersecurity Framework 2.0 to keep ownership, monitoring, and exception handling consistent.

Risk and Threat Considerations

Information barriers fail when organisations treat them as a policy statement instead of an enforced control. The main risks are accidental leakage, deliberate circumvention, and weak exception handling, especially where employees can use alternate channels or where the barrier is not kept in sync with changing team membership and business need.

Failure mechanism: The barrier breaks down when the same people retain access to shared tools, forwarding paths, or collaboration spaces that bypass the intended separation, or when exceptions are granted without time limits and review.

Impact: Sensitive deal information, legal strategy, client data, or regulated communications can cross the boundary, creating compliance exposure, conflicts of interest, investigation risk, and potential unfair-information advantage.

In practice, the control should be treated as a data-loss reduction and conduct-control measure, not as a guarantee that every relevant communication is blocked. The more fragmented the organisation’s collaboration stack, the more likely it is that uncontrolled side channels will weaken the intended separation.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

NIST CSF 2.0 and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 define the regulatory obligations.

Framework	Control / Reference	Relevance
ISO/IEC 27001:2022	A.5.15 — Access Control	Barrier design depends on restricting who can communicate across defined groups.
Recommendation — Define and enforce access restrictions that separate the affected user groups.
NIST CSF 2.0	PR.AC — Identity Management, Authentication, and Access Control	The control aligns with governing who may interact across restricted boundaries.
Recommendation — Apply access-control policies that enforce group separation and exception handling.
CIS Controls v8	6 — Access Control Management	Restricting communication between groups is an access-management control problem.
Recommendation — Manage access paths so only approved interactions can cross the barrier.

Practitioner Guidance

What to verify: Confirm that the barrier is defined around actual communication paths, not just named user groups. If people can still reach each other through shared drives, chats, calendars, or forwarding rules, the control is incomplete.

Decision rule: If the reason for separation is regulatory, due diligence, or conflict management, require a documented owner, explicit exception process, and expiry dates for any temporary override. If none of those exist, treat the barrier as a weak administrative measure rather than a reliable control.

What practitioners underestimate: The hardest part is usually not initial blocking, but ongoing governance. Group membership changes, business exceptions accumulate, and the barrier can quietly decay unless someone is accountable for review and removal.

Practitioner takeaway: Use information barriers when the organisation must prevent contact between groups as a matter of governance, and validate them against real communication behaviour, not just policy intent.