Attorney-client privilege is the common-law doctrine that confidential communications between a lawyer and client made for the purpose of seeking or providing legal advice are protected from compelled disclosure. Survives the lawyer-client relationship indefinitely. Held by the client (the lawyer cannot waive it unilaterally). The bedrock of the lawyer’s ability to give honest counsel without exposing the client to consequences for that honesty.
What it means in practice
The privilege protects content, not facts. A client cannot withhold underlying facts (what happened, who was where, what they did) by routing them through the lawyer; the privilege protects the conversation about the facts, not the facts themselves. The privilege also has structural limits: it does not protect communications made in furtherance of a crime or fraud (the crime-fraud exception), it can be waived inadvertently by sharing privileged material with third parties, and it can be lost by including non-essential parties in the conversation (the “common interest doctrine” lets co-defendants share, but the boundary is narrow). For the digital era: privileged email forwarded to a personal Gmail, copied into an unsecured Slack, or stored in a non-firm cloud account is at risk of waiver. Courts split on whether the firm’s electronic security failures equate to the client’s waiver.
Who it affects, and how
Affects every lawyer-client relationship, every privileged document, every legal-advice conversation. The operational stakes are highest for: corporate counsel handling internal investigations (one careless email to a non-counsel manager can blow the privilege over the entire investigation), criminal defense lawyers communicating with detained clients (jail email and phone systems are not privileged channels in most jurisdictions, despite the legal label sometimes attached), and lawyers practicing across jurisdictions where the privilege rules differ (US privilege is broader than the EU “legal professional privilege,” which has narrower coverage of in-house counsel). For clients, the practical lesson is that privilege protects the conversation only if the channel was actually confidential and the participants were limited to those required for the advice.
What you can change today
For lawyers: audit the channels used to communicate privileged content this week. Confirm that the firm email, the firm chat, and the firm document store are configured for privilege protection (encryption in transit and at rest, access controls per matter, retention policies that survive subpoenas without surrendering privileged content). Disable forwarding to personal devices on privileged matter accounts. For clients: do not communicate substantive legal strategy in any channel your lawyer did not approve. Do not copy the lawyer on a discussion with non-counsel parties unless you understand the privilege implications. The lawyer should be the gatekeeper of what is privileged and what is not.