bluebookify

Context-aware Bluebook citation formatting powered by LLMs.

Extracts citations from legal text — case citations, statutory references, short forms, and signals — and corrects their formatting to Bluebook standard. Only the citation contexts (not the full document) are sent to the LLM, making it token-efficient and privacy-conscious.

Install

npm install bluebookify

Quick start

import { bluebookify } from 'bluebookify'

const result = await bluebookify(
  'See Marbury v Madison, 5 US 137 (1803). The Court held that...',
  { apiKey: process.env.OPENAI_API_KEY, provider: 'openai' }
)

result.text
// → 'See *Marbury v. Madison*, 5 U.S. (1 Cranch) 137 (1803). The Court held that...'

result.corrections
// → [{ position: 4, original: 'Marbury v Madison, 5 US 137 (1803)', replacement: '*Marbury v. Madison*, 5 U.S. (1 Cranch) 137 (1803)', context: '...' }]

result.unchanged
// → false

Providers

Built-in support for any OpenAI-compatible API, plus a native Anthropic adapter.

Provider	Default model	Notes
openai	gpt-4o-mini
anthropic	claude-haiku-4-5-20251001	Native adapter (different API format)
gemini	gemini-2.0-flash	OpenAI-compatible endpoint
groq	llama-3.3-70b-versatile
together	meta-llama/Meta-Llama-3.1-8B-Instruct-Turbo
mistral	mistral-small-latest
xai	grok-3-mini-fast
deepseek	deepseek-chat
openrouter	(none — must specify model)

Override the default model:

const result = await bluebookify(text, {
  apiKey: process.env.OPENAI_API_KEY,
  provider: 'openai',
  model: 'gpt-4o',
})

Custom LLM function

Bypass the built-in client entirely:

const result = await bluebookify(text, {
  llm: async (messages) => {
    const res = await myLlmCall(messages)
    return res.text
  },
})

Options

Option	Type	Default	Description
apiKey	string	—	API key for the LLM provider
provider	Provider	—	Provider name (maps to base URL + default model)
model	string	(per provider)	Model name. Required if no provider default.
baseURL	string	—	Custom endpoint URL. Overrides provider mapping.
llm	(messages) => Promise<string>	—	Custom LLM function. Overrides apiKey/provider/model.
rules	string	""	Custom rules prepended to the system prompt
contextSize	number	100	Characters of context on each side of a citation
batchSize	number	20	Maximum citations per LLM call

You must provide either apiKey (with provider or model) or llm.

Result

interface BluebookifyResult {
  text: string          // The corrected text
  corrections: Array<{  // Only citations that were changed
    position: number    // Index in original text
    original: string    // What was there
    replacement: string // What it became
    context: string     // Surrounding snippet for audit
  }>
  unchanged: boolean    // true if nothing was modified
}

No citations in text: LLM is not called. Returns immediately with unchanged: true.

All citations already correct: LLM is called (correctness can't be pre-judged), but corrections is empty and unchanged is true.

Custom rules

Pass domain-specific rules via the rules option. Works with lexstyle for structured rule management:

import { rules, serialize } from 'lexstyle'
import { bluebookify } from 'bluebookify'

const result = await bluebookify(text, {
  apiKey: process.env.OPENAI_API_KEY,
  provider: 'openai',
  rules: serialize(rules, 'citations'),
})

Or pass rules as a plain string:

const result = await bluebookify(text, {
  apiKey: '...',
  provider: 'openai',
  rules: `Italicize case names. Use "U.S." not "US" for reporters.
Use Id. for immediately preceding authority. Use en dashes for page spans.`,
})

Design decisions

Extract-and-send. Citations are discrete, identifiable chunks. Regex extracts them with surrounding context, and only those snippets are sent to the LLM. A 10,000-word brief with 15 citations sends ~15 small context windows, not 10,000 words.

Wide context windows. Default context size is 100 characters (vs 50 for dashes) because citations are longer and the LLM needs to see signals, parentheticals, and preceding/following citations to determine short-form vs full-cite relationships.

Signal inclusion. Introductory signals (See, Cf., But see, etc.) immediately before a citation are merged into the extraction, so the LLM can format them as a unit.

Batch validation. Each batch response is validated against its expected IDs before merging. Missing or unknown correction IDs are caught immediately.

Robust response parsing. LLM output is parsed via strict JSON first, with a hardened bracket-extraction fallback that skips stray brackets in preamble text.

Development

npm install
npm test
npm run typecheck
npm run build     # ESM + CJS + .d.ts

License

Apache-2.0