How to Train Claude on Your Writing Style (Reference Document Prompting)

The Technique Most Lawyers Miss

Every prompt in our prompt library produces useful output. But generic prompts produce generic output. One technique closes the gap: reference-document prompting.

The concept is simple. Paste a document you wrote before — a demand letter, a motion, an engagement letter, a client memo — and tell Claude to follow its style, structure, and conventions. Claude reads the reference and mirrors your voice, formatting, and level of detail.

Why Reference Documents Work

Claude's 200,000-token context window holds your reference document and your new instructions simultaneously. Claude extracts patterns: how you structure arguments, where you place citations, how formal your tone is, whether you use numbered paragraphs or narrative prose, how you handle defined terms.

This works because Claude learns from context, not from memory. Every conversation starts fresh. But within a conversation, anything you paste becomes active context. A 15-page motion you wrote last year teaches Claude more about your style than any written instruction.

Step 1: Choose the Right Reference

Pick a document that represents your best work in the same category as what you need. Writing a demand letter? Paste your strongest demand letter. Drafting a motion to dismiss? Paste one you filed and won.

The reference should match on three dimensions:

• Document type — same category (motion, letter, memo, agreement)
• Complexity level — similar depth and length to what you need
• Audience — same reader (court, opposing counsel, client, partner)

A corporate M&A memo will not teach Claude how to write a family law client letter. Match the context.

Step 2: Structure the Prompt

Use this three-part structure: reference document, instructions, and new inputs.

Here is a [DOCUMENT TYPE] I wrote previously. Use it as a style and format reference for the new document I need.

REFERENCE DOCUMENT:
[PASTE YOUR PREVIOUS DOCUMENT]

---

Now draft a new [DOCUMENT TYPE] with the following details:

[YOUR NEW FACTS, PARTIES, ISSUES, ETC.]

Match the reference document's:
- Tone and formality level
- Section structure and headings
- Citation style and placement
- Level of detail and analysis depth
- Defined terms conventions

The explicit "match the reference" instructions matter. Without them, Claude may use the reference as background context rather than as a style template.

Step 3: Refine with Follow-Ups

The first output will be close but not exact. Close the gap with targeted follow-ups:

• "The reference uses numbered paragraphs — switch to that format."
• "My firm cites cases with the full name on first reference, then short form. Apply that convention."
• "The analysis sections in my reference are longer. Expand the analysis here to match."
• "Remove the headers — my demand letters use continuous prose, not sections."

Each follow-up teaches Claude something specific about your preferences. After two or three rounds, the output should feel like your own work.

Advanced: Multiple References

For recurring document types, paste two or three examples. Claude identifies patterns across them — the consistent elements become the template, and the variations show Claude where to adapt.

Here are three engagement letters I've written for different practice areas. Use them as style references.

REFERENCE 1 (litigation):
[PASTE]

REFERENCE 2 (corporate):
[PASTE]

REFERENCE 3 (real estate):
[PASTE]

---

Now draft an engagement letter for a new employment law matter:
[DETAILS]

Match the consistent formatting, tone, and structure across all three references. Adapt the scope and terms sections for employment law.

Three references give Claude enough data to distinguish your firm's conventions from matter-specific content.

What Works Best as a Reference

Some document types benefit from reference prompting more than others:

• High value: Demand letters, client memos, engagement letters, motions, settlement proposals — any document with a distinctive firm style
• Medium value: Discovery responses, deposition summaries, contract review memos — structured documents where format consistency matters
• Lower value: Research memos, case summaries — content-driven documents where style matters less than substance

Common Mistakes

• Using a weak reference. Claude mirrors whatever you give it. If the reference is poorly organized or verbose, the output will be too. Choose your best work.
• Skipping the explicit instructions. "Here's my old letter, write a new one" gives Claude ambiguity about what to preserve. List what to match: tone, structure, citations, detail level.
• Providing a reference from a different document type. A brief does not teach Claude how to write a client email. Match the category.
• Ignoring confidentiality. Before pasting any document, redact client-identifying information or use Claude Team/Enterprise plans with zero data retention. See our AI ethics guide for confidentiality protocols.

Building a Reference Library

Keep a folder of your strongest documents organized by type. When you need Claude to draft something new, pull the closest match. Over time, this library becomes your firm's style guide — enforced not by a manual nobody reads, but by AI that applies it on every document.

For more on structuring effective prompts, see our CRAFT prompting framework. Browse ready-to-use templates in the prompt library.