Claudeによる社外弁護士請求書監査スキル

---
name: outside-counsel-bill-auditor
description: Audit an outside-counsel invoice line-by-line against the firm's billing guidelines. Returns a structured Markdown report with per-line citations, the guideline violated, and a recommended adjustment per finding. Never adjusts the bill automatically — the legal-ops lead reviews and decides.
---

# Outside-counsel bill auditor

## When to invoke

Use this skill when a legal-ops lead has an outside-counsel invoice (LEDES 1998B/1998BI/2000 or pre-parsed CSV) and the firm's billing guidelines, and wants a structured audit before the invoice is approved or disputed.

Do NOT invoke this skill for:

- **Auto-reducing the bill.** The skill flags; humans decide. Auto-deducting based on findings damages the outside-counsel relationship and may violate the engagement letter's dispute procedure.
- **AFA-billed engagements.** The skill is calibrated to hourly billing.
- **Bills the firm has already approved.** Audit happens before approval, not after.

## Inputs

- Required: `invoice_path` — path to the LEDES file or pre-parsed CSV.
- Required: `guidelines_path` — path to the firm's billing guidelines file (see `references/1-billing-guidelines-template.md`).
- Optional: `engagement_letter_overrides_path` — per-matter overrides to the firm guidelines.
- Optional: `firm_name` — outside firm name, for the per-firm calibration section of the report.

## Reference files

- `references/1-billing-guidelines-template.md` — the firm's guidelines shape.
- `references/2-ledes-parser-notes.md` — LEDES format parsing notes.

## Method

Six steps.

### 1. Validate the invoice format

Parse the LEDES file or CSV. Halt with a parse-error report if the format is malformed. Check that required columns are present: `line_id`, `date`, `timekeeper`, `timekeeper_role`, `task_code`, `activity_code`, `hours`, `rate`, `amount`, `narrative`.

### 2. Run deterministic checks

Without invoking the LLM, flag:

- **Block-billing**: a single time entry with a narrative containing multiple distinct task verbs (e.g. "Reviewed contract; drafted letter; called client" in 2.4 hours). Flag at >2 verbs unless the engagement letter explicitly permits.
- **Expense double-entry**: the same `line_id` or `expense_id` referenced twice.
- **Staffing-ratio breach**: partner hours on a `task_code` the guidelines name as associate-or-below work (default: legal research, deposition summaries, document review).
- **Premium-time cap breach**: off-hours surcharge entries totaling more than the engagement letter's monthly cap.
- **Rate variance**: timekeeper rate that deviates from the engagement letter's rate sheet by more than ±2%.

### 3. Read the guidelines

Load `guidelines_path` and the engagement-letter overrides if present. The guidelines define the comparison anchors for steps 4 and 5. SHA-256 the guidelines for the audit log.

### 4. Per-line LLM evaluation

For lines not flagged by deterministic checks, evaluate against the guidelines for prose-judgment violations:

- **Vague time entries** — "0.6h research" without naming the issue researched, the source consulted, or the deliverable.
- **Scope-creep signals** — work on a topic outside the engagement letter's matter scope.
- **Should-be-flat-fee work** — work that the engagement letter explicitly bundled into a flat fee but appears as a separate hourly line.
- **Internal-conference billing** — multiple timekeepers on the same internal conference where the guidelines limit attendees.

For each finding, cite:
- `line_id`
- `guideline_section_id` (or "no matching guideline" if the finding is intuitive but not codified)
- `recommended_adjustment` — dollar amount or "negotiate" tag
- `confidence` — `high` (clear violation), `medium` (likely violation, judgment call), `low` (signal worth surfacing, may be defensible)

### 5. Aggregate by guideline category

Group findings by violation category. Total hours and dollars by category. The aggregate is the negotiation lever — "block-billing on 23 lines totaling $4,200" is a stronger negotiation point than 23 individual line disputes.

Per-firm calibration: if `firm_name` is provided AND the audit log has prior runs for the same firm, surface the trend ("block-billing rate this month: 9%; prior 6-month average: 12%; trending down").

### 6. Emit report + audit log

Write the report to stdout in the format below. Append one JSONL line to `audit/<YYYY-MM>.jsonl`:

```json
{
  "audit_id": "uuid",
  "timestamp": "ISO-8601",
  "invoice_id": "...",
  "firm_name": "...",
  "invoice_total_usd": 0,
  "guidelines_sha": "...",
  "findings_by_category": {
    "block_billing": { "count": 0, "hours": 0, "dollars": 0 },
    "vague_entries": { "count": 0, "hours": 0, "dollars": 0 },
    ...
  },
  "skill_version": "1.0",
  "model": "claude-sonnet-4-6"
}
```

## Output format

```markdown
# Bill audit — {firm_name} — {invoice_id}

Audited: {ISO timestamp} · Invoice total: ${total} · Skill v1.0

{PER-FIRM TREND if firm_name has prior runs}

## Aggregate findings

| Category | Lines | Hours | Dollars |
|---|---|---|---|
| Block-billing | 23 | 47.2 | $14,160 |
| Vague entries | 18 | 12.6 | $3,780 |
| Staffing-ratio breach | 4 | 8.0 | $4,800 |
| Premium-time cap breach | 2 | 6.0 | $2,250 |
| Rate variance | 1 | 0.8 | $40 |

Total flagged: $25,030 of $187,400 (13.4%).

## Findings — high confidence

### Block-billing — line 142
- **Narrative:** "Reviewed contract; drafted comments; called opposing counsel" — 2.4h
- **Guideline:** §3.2.a (no time entry shall combine more than one task)
- **Recommended adjustment:** request narrative split into 3 entries; adjust if split shifts hours

### Staffing-ratio breach — line 287
- **Narrative:** "Document review for production" — 4.0h, partner timekeeper rate $850/hr
- **Guideline:** §4.1 (document review staffed at associate level or below)
- **Recommended adjustment:** rebill at junior associate rate ($375/hr); $1,900 reduction

## Findings — medium confidence

(per-line entries with `confidence: medium`)

## Findings — low confidence (informational)

(per-line entries with `confidence: low`)

## Provenance

- Guidelines: `firm-billing-guidelines.md` — SHA `{short}`
- Engagement letter: `engagement-letters/<matter>.md` (if used)
- Audit record: `audit/2026-05.jsonl` line {N}
```

## Watch-outs

- **Auto-adjustment drift.** *Guard:* output ends with the structured report; no "adjusted bill" output.
- **Confidentiality of attorney work-product.** *Guard:* invoice narratives are privileged. Process via API access with zero-retention; do not paste invoices into shared chat surfaces.
- **Over-disputing damages firm relationship.** *Guard:* per-firm trend tracking surfaces dispute-volume drift.
- **Hallucinated guideline citations.** *Guard:* every finding cites `guideline_section_id`; findings without a citable section get "no matching guideline" tag rather than fake citations.

# Outside-counsel billing guidelines template

The bill auditor reads guidelines in this shape. Copy this file to `firm-billing-guidelines.md` (or wherever your skill config points), fill in the firm-specific values, and version it in git.

The guidelines are the comparison anchor. Without them the skill has nothing to audit against. Most law departments revise these annually; the skill captures the file's SHA per audit so changes are visible.

## Section IDs

Every guideline carries an ID (`§1.1`, `§3.2.a`, etc.). The skill's findings cite the ID. If you renumber, the audit log's prior findings still reference the old IDs — keep a renumbering mapping or treat renumbering as a guideline-version bump.

## §1 — Engagement scope and pre-approval

- **§1.1** All matters require a written engagement letter naming the matter, the timekeepers, the rate sheet, the budget, and any flat-fee components.
- **§1.2** Work outside the named scope requires written pre-approval from the assigned in-house attorney.
- **§1.3** Budget overruns >10% require written notice within 5 business days; overruns >25% require pre-approval before further work.

## §2 — Timekeeper composition

- **§2.1** Use of new timekeepers (not on the engagement letter's rate sheet) requires written approval before time is billed.
- **§2.2** The rate sheet is fixed for the engagement's duration unless an annual rate adjustment is provided in writing 60 days in advance.
- **§2.3** Rate variance from the rate sheet on any line is a violation regardless of intent.

## §3 — Time entry detail

- **§3.1** Every time entry shall name (a) the task verb, (b) the specific deliverable or document, (c) the issue or matter focus.
  - *Example pass:* "Drafted §4 (Indemnification) of MSA between Acme and BetaCo, focused on caps and carve-outs."
  - *Example fail:* "Worked on contract."
- **§3.2.a** No single time entry shall combine more than one distinct task.
  - Block-billing definition: a narrative containing more than 2 distinct task verbs (drafted, reviewed, called, attended, researched, etc.).
- **§3.2.b** Minimum increment: 0.1 hour. No 0.05h or smaller entries; no rounded-up entries (e.g. 0.5h for what was actually 0.2h work).
- **§3.3** No "review" entry without naming what was reviewed and the outcome of the review.

## §4 — Staffing ratios

- **§4.1** Document review shall be staffed at associate level or below. Partner time on document review requires written justification.
- **§4.2** Legal research shall be staffed at associate level or below. Partner time on research requires written justification (novel issue, conflict).
- **§4.3** Deposition summaries shall be staffed at paralegal or associate level. Partner / senior counsel time only when the substance requires.
- **§4.4** Client conferences shall not have more than 2 outside-firm timekeepers attending unless pre-approved.
- **§4.5** Internal outside-firm conferences shall not bill more than 2 outside timekeepers unless the conference involves substantive case strategy and is documented as such.

## §5 — Expenses

- **§5.1** Expenses shall be billed at cost. No markup on photocopying, courier, transcript fees, computer research (Westlaw / Lexis), or travel.
- **§5.2** Travel: economy class for flights under 6 hours; business class permitted for transoceanic. Hotel at standard corporate rate, no luxury class without approval.
- **§5.3** Meals: $50 per person per day cap unless client-facing meal with documented rationale.
- **§5.4** No charge for in-firm administrative time (secretarial, file management, billing-related work).
- **§5.5** Computer research: at-cost only. No proration of monthly subscription fees onto matters.

## §6 — Premium time

- **§6.1** Standard hourly rates apply Monday-Friday 7am-9pm in the timekeeper's local time zone.
- **§6.2** Off-hours premium (1.25× standard) requires explicit pre-approval per matter.
- **§6.3** Off-hours premium cap: $5,000 per matter per month, absent written waiver.

## §7 — Discounts and adjustments

- **§7.1** A 10% timely-payment discount applies if the firm pays within 30 days of invoice receipt.
- **§7.2** Disputed lines remain disputed until resolved; the firm may pay the undisputed portion within terms without losing the discount on that portion.

## §8 — LEDES and submission format

- **§8.1** All invoices shall be submitted in LEDES 1998BI or 2000 format unless the firm has approved a paper or PDF alternative in writing.
- **§8.2** Each line shall include `task_code` (UTBMS) and `activity_code` (UTBMS) values from the engagement letter's permitted list.
- **§8.3** Invoices shall be submitted within 30 days of month-end. Late invoices may be rejected.

## How the skill uses each section

- **Deterministic checks**: §3.2.a (block-billing verb count), §3.2.b (minimum increment), §4.1-§4.4 (staffing ratios when timekeeper roles are tagged), §5.1 (expense double-entry detection), §6.3 (premium-time monthly cap), §2.3 (rate variance).
- **LLM evaluation**: §3.1 (time-entry detail quality — pass/fail per narrative), §3.3 (review-entry quality), §5.4 (administrative-time detection in narratives), §7 / §8 (compliance posture).

## Customizing the template

When you adapt this template:

1. Add or remove sections to match the firm's actual guidelines. Don't keep template language that doesn't reflect the firm's policy.
2. Renumber IDs only when necessary; cross-reference old IDs in the changelog so audit-log entries stay interpretable.
3. Document the engagement-letter override path — most law departments allow per-matter exceptions to specific sections.

# LEDES parser notes

The bill auditor's deterministic checks operate on parsed line-item records. Most outside-counsel firms in the US ship invoices in LEDES (Legal Electronic Data Exchange Standard) format. This file documents the formats the skill handles and the per-format quirks.

## Supported formats

### LEDES 1998B (legacy)

- Pipe-delimited flat file. Header row + data rows.
- Each row represents one billed item (time or expense).
- Columns are positional, not named — the parser maps by position per the LEDES 1998B spec.
- Limited expense-detail granularity; expense category is one of ~20 codes.

### LEDES 1998BI (international)

- Same shape as 1998B with currency-code and tax fields added.
- Used by firms billing outside the US or in multiple currencies.
- The skill normalizes amounts to the engagement-letter base currency before deterministic checks.

### LEDES 2000 (XML, less common)

- XML format; richer schema including matter / sub-matter hierarchy and structured timekeeper records.
- The skill parses the timekeeper section once per invoice and joins to time entries by `timekeeper_id`.
- Most US firms still ship 1998B/1998BI; LEDES 2000 is more common in EU.

## Required columns (after parsing)

The skill expects each line, regardless of source format, to land in this normalized shape:

| Column | Type | Notes |
|---|---|---|
| `line_id` | string | Unique within the invoice. |
| `date` | ISO-8601 date | Date the work was performed. |
| `timekeeper_id` | string | LEDES timekeeper ID. |
| `timekeeper_name` | string | Display name. |
| `timekeeper_role` | string | `partner`, `senior_associate`, `associate`, `paralegal`, `other`. The skill needs role to apply staffing-ratio guidelines. |
| `task_code` | string | UTBMS task code (e.g. `L110` for legal research). |
| `activity_code` | string | UTBMS activity code (e.g. `A101` for plan and prepare for). |
| `hours` | number | 0 for expense lines. |
| `rate` | number | The hourly rate billed. 0 for expense lines. |
| `amount` | number | Line total. |
| `narrative` | string | The free-text time-entry description. |
| `is_expense` | boolean | True for expense lines. |
| `expense_category` | string | UTBMS expense code if `is_expense`; null otherwise. |

## Per-format quirks

### LEDES 1998B narrative width

The 1998B spec doesn't cap narrative width, but some submission portals truncate at 250-500 chars. Firms occasionally submit truncated narratives that look vague when they were originally detailed. The skill flags very-short narratives but does not auto-assume truncation; the legal-ops lead checks the source.

### Timekeeper role inference

LEDES doesn't include a `role` field directly. The skill infers role from the engagement letter's rate sheet (timekeeper rates tier into roles) OR from a per-firm `timekeeper_roles.csv` mapping if provided.

If neither is available, the skill flags every line where role-dependent guidelines (§4.x) apply as "role unknown — staffing check skipped" rather than guessing.

### Expense detail granularity

LEDES 1998B has a coarse expense category. For finer detail (e.g. distinguishing photocopying from CD-ROM duplication), the skill reads the `narrative` field of expense lines. Firms vary in how detailed expense narratives are.

### Partial-hour rounding

LEDES preserves the actual hours billed; rounding (or non-rounding) is the firm's policy. The skill doesn't enforce rounding policy — that's the engagement letter's job. The skill does flag suspicious patterns (every entry ending in .0 or .5, suggesting the firm rounds aggressively).

## CSV fallback

For invoices not in LEDES format (small firms, paper invoices, PDF-extracted), the skill accepts a CSV with the same normalized columns above. The CSV must:

- Use comma delimiter, double-quote text qualifier, UTF-8 encoding.
- Include header row.
- Use ISO-8601 dates.

A pre-parsed CSV is the recommended format when a PDF invoice has been OCR'd — manual cleanup of the CSV is more reliable than auto-extraction from PDF, which often loses table alignment.

## Audit-log line storage

The audit log captures `findings_by_category` (aggregated) and per-line findings IDs, NOT the full invoice. Rationale: invoice content is privileged; the audit log should be retainable longer than the invoice and shouldn't carry the privileged content.

For full reproducibility of a finding, the legal-ops lead can re-run the skill against the original invoice file (which lives in the e-billing platform's record).

## What the skill does NOT do

- Calculate the dispute total (the legal-ops lead picks which findings to dispute).
- Communicate findings to the outside firm (the legal-ops lead handles the conversation).
- Enforce a fixed dispute response window (the engagement letter governs).
- Decide whether the finding is worth disputing relative to the firm relationship.

The skill is decision support, not negotiation automation.