Need-to-know is the principle that information is shared only with those whose role requires it for their work. Inverts the default of corporate or social communication, where information flows by relationship rather than necessity. Adopted from US intelligence-community access controls (the formal version: classified information requires both clearance and “need-to-know” before disclosure).
What it means in practice
The civilian application is structural and editorial. Structural: a source’s identity is not in a calendar invite, not in a Slack channel, not in a shared drive, not on a sticky note on a colleague’s monitor; it lives only in the head of the journalist with whom contact is established, plus possibly the editor with veto power over publication. Editorial: when a colleague asks “who is the source on this,” the answer is usually “I cannot tell you that,” not because of mistrust but because the colleague does not need that information to do their job, and any expansion of the knowing-set increases the surface area for accidental or coerced disclosure. The discipline applies equally to lawyers (who knows about the client’s strategy), to NGO staff (who knows the names of in-country contacts), to executives in M&A (who knows the target name before announcement).
Where it shows up
Most consequential in: journalism (the source-protection literature is full of cases where a third party learned an identity informally and accidentally exposed it), legal practice (privilege requires the conversation to be confined to client and counsel; expansion to a paralegal who didn’t need the detail can collapse the privilege), corporate security (insider-trading enforcement traces the chain of people who learned material non-public information), and family safety (a domestic-violence survivor’s new address is told to the minimum number of people because each person told is one more potential leak under social pressure or coercion). The default cultural assumption (more sharing equals more trust) inverts in operational settings.
What you can change today
Look at the three most sensitive pieces of information you currently hold. For each, list everyone who knows. For each person on the list, ask: do they actually need to know to do their job. The names that fail the test are the names you stop telling, even when the conversation makes it easy. The discipline is awkward at first because the cultural pressure is to share. The defense the discipline buys becomes visible only when the disclosure scenario actually arrives, by which point it is too late to retroactively stop telling someone something.