Custom, Not Cookie-Cutter: How Lighthouse AI Delivered a Tailored 200K Privilege Log

The Challenge

In a high-stakes regulatory investigation for a heavily regulated client, outside counsel faced a massive task: produce a 200,000-entry privilege log with specificity, consistency, and speed—without drawing regulatory fire.  

The Lighthouse Solution

Lighthouse’s GenAI-powered privilege log solution gave outside counsel something neither traditional privilege log methods or other GenAI privilege log solutions could: customized, defensible entries at scale—with almost no manual drafting by review teams or outside counsel.

What set it apart? The human-in-the-loop model. Lighthouse AI experts partnered with the legal team to fine-tune outputs for that matter’s unique needs, iterating on key components of each log line until the results were exactly right.

Why It Worked

Rather than force-fit the log into one-size-fits-all templates or get stuck with GenAI outputs that weren’t a good fit for this very unique matter, Lighthouse tailored and continuously iterated our GenAI prompting across three key dimensions:

• Document Type (e.g., Email, Memo)
• Legal Hook (Why the document is privileged e.g., “requesting legal advice”)
• Subject Matter (What the privileged information is generally regarding)

How We Did It

Outside counsel needed subject matter descriptions to be as specific as possible without giving away privilege content, while creating uniformity across the document type and legal hooks based on the unique documents at issue in the investigation.  

Through prompt engineering and targeted feedback with outside counsel, the AI’s first draft evolved from raw potential to precision output that exactly met their needs:

• 100+ document types condensed to a consistent set of 9 that outside counsel needed ‍
• 80+ legal hooks refined down to 8, specific to the way attorneys worked at the underlying company ‍
• 120,000+ unique Re: line descriptions that explained specific legal projects and work, none reused more than 1% of the time

The Results

• 200K+ log entries generated on a tight timeline
• No vague or red-flag phrasing—achieved by iterating with GenAI prompts to ensure that negative language caught in QC was removed across the entire privilege log
• Near-zero manual drafting by the legal team
• Custom configurations (e.g., suppressing references to specific entities) tailored to client preferences
• Focused QC efforts where it mattered—resulting in massive time and cost savings

The ROI

Outside counsel’s job? Review, not write.

By shifting their time to targeted QC and feedback instead of manual drafting, the legal team met their deadline under pressure—and under budget.