Why Your Post-Mortem Can Be Used Against You
In civil litigation, the opposing party's lawyers have the right to Discovery — a legal process that compels you to hand over internal documents, emails, Slack messages, Jira tickets, and reports that are relevant to the case. There is no "we kept it internal" exception. If it was written down and it's relevant, it can be demanded.
This creates a dangerous dynamic: the same culture of radical transparency that makes engineering teams better — writing honest post-mortems, documenting what went wrong, acknowledging failures — can generate a paper trail that becomes devastating in litigation.
A post-mortem that reads: "We were aware of this vulnerability for six months and deprioritized the fix due to feature pressure" is an accurate, honest, and useful engineering document. It is also, in a lawsuit, evidence of negligence.
The Solution: Attorney-Client Privilege
Attorney-Client Privilege is a legal protection that shields communications between a client and their attorney from being disclosed in legal proceedings. When an internal investigation is conducted at the direction of legal counsel, for the purpose of providing legal advice, the resulting documents can be protected from discovery.
To establish this protection, the following conditions must be met:
1. Legal Direction
The investigation must be formally initiated and directed by the Legal Department, not Engineering. In practice, this means the General Counsel or outside counsel sends a written memo stating: "I am directing this investigation for the purpose of providing legal advice to the company." Engineering still does the technical work, but the legal framing is established.
2. Document Marking
Every document produced as part of the privileged investigation must be clearly marked at the top:
PRIVILEGED AND CONFIDENTIAL
ATTORNEY-CLIENT COMMUNICATION
PREPARED AT THE DIRECTION OF COUNSEL
DO NOT DISTRIBUTE
3. Controlled Distribution
The report is not shared via company-wide email, Slack channels, or Confluence pages. It is distributed only to the specific individuals who need it for legal purposes. The moment a privileged document is shared broadly, the privilege can be considered waived — and the document becomes discoverable.
4. Separate the Technical Remediation Track
The privileged investigation (for legal purposes) runs in parallel with the technical remediation track (for fixing the system). The technical team's operational runbooks, monitoring dashboards, and deployment logs are generally not privileged — but the analysis and conclusions drawn from them, when done under legal direction, can be.
What Engineers Must Never Write
The following phrases, written in any non-privileged channel (Slack, Jira, email, public post-mortem), create legal liability:
| Phrase | Why It's Dangerous |
|---|---|
| "We were negligent in..." | "Negligence" is a legal standard. You've just admitted it. |
| "We knew about this risk and chose not to fix it." | Establishes knowledge and deliberate inaction — the worst combination. |
| "This was completely preventable." | Implies the company failed to take reasonable precautions. |
| "We should have caught this months ago." | Establishes a timeline of known risk. |
The correct approach: stick to technical facts in non-privileged channels. "The patch for CVE-2024-XXXX was not applied to the production cluster." That is a fact. Whether that constitutes negligence is a legal determination — let the lawyers make it.
Interviewers for VP Engineering, CISO, or Staff SRE roles sometimes ask: "How do you balance blameless post-mortems with legal risk?" The nuanced answer: blameless post-mortems remain the right engineering practice, but in high-stakes incidents involving potential litigation, a second privileged report is produced under legal direction. The engineering post-mortem focuses on system improvement; the privileged report addresses legal exposure. They are separate documents with separate audiences and separate protections.