Claude(법률 데이터 접근)와 전문 법률 AI(Westlaw/Lexis)의 성능 비교: 1:1 테스트 결과

AI 시대가 시작된 지 몇 년이 지난 지금, 법률 AI 기술은 두 가지 방향으로 나뉘고 있는 것 같습니다. 한쪽에는 Claude나 ChatGPT 같은 범용 AI 시스템이 있고, 다른 한쪽에는 Westlaw의 AI Deep Research나 Lexis Protege와 같은 목적 기반의 법률 AI 시스템이 있습니다.

저희는 Claude와 Westlaw를 모두 정기적으로 사용하는 두 명의 현직 소송 변호사(Ding과 Duff)입니다. 다양한 시스템이 법률 연구를 얼마나 잘 수행하는지 궁금해서, 세 가지 시스템 모두에 대해 5가지 프롬프트를 사용하는 일련의 비교 테스트를 진행하기로 했습니다. 결과가 흥미롭다고 생각되어 공유하고자 합니다.

Claude 자체는 판례나 법령에 접근할 권한이 없습니다. 저희는 DingDuff라는 커넥터를 직접 만들어 사용했습니다(Anthropic API 키를 직접 제공하면 현재는 무료로 사용할 수 있습니다). 아래에서 논의하겠지만, DingDuff를 사용하면 Claude가 판례와 법령을 검색하고 가져올 수 있습니다. 하지만 무엇을 어떻게 연구할지에 대한 결정은 Claude가 내립니다(판례 연구 스킬 파일을 포함하거나 제외하고 테스트를 진행해봤지만 큰 차이는 없었습니다).

이번 테스트의 흥미로운 결과 중 하나는 Claude가 AI 시스템으로서 얼마나 빠르게 발전했는지를 보여준다는 점입니다. 이 결과물들은 대부분 2026년 4월 말, 최신 버전의 Claude co-work를 사용하여 생성되었으며, 저희가 보기에는 매우 인상적입니다. 1년 전에는 Claude가 이런 결과물을 만들어낼 수 없었을 것입니다.
이 5가지 프롬프트는 다양한 주와 다양한 법률 분야를 다루기 위해 만들어진 가상의 사실 관계이지만, 저희가 실제로 사용하는 프롬프트와 유사하게 작성하려고 노력했습니다.

The prompts

|  | Prompt |
|---|---|
| **1** | **Adverse Possession — Walton County, GA.** Prepare a memo analyzing my client's position in a boundary dispute in Walton County, Georgia. In 1998 my client's predecessor-in-title built a barbed-wire fence intended to follow the surveyed boundary between two rural parcels. A 2024 survey revealed that the fence encroaches approximately 12 feet onto the adjoining owner's land over a 400-foot run, enclosing roughly 4,800 square feet. My client bought the property in 2011 and has continuously grazed cattle on the enclosed strip; his predecessor used it for pasture from 1998 to 2011. The record owner has paid property taxes on the disputed strip throughout. The neighbor first objected in late 2025 and has threatened ejectment. Please address: (1) whether my client can establish title by adverse possession (20-year) or prescription (7-year under color of title) under relevant Georgia statutes and case law; (2) whether tacking between predecessors is available on these facts; (3) whether the hostility element can be satisfied when the parties mutually (but mistakenly) believed the fence sat on the true line — i.e., the "mistaken boundary" line of authority; (4) the effect, if any, of the record owner's tax payments; and (5) the procedural vehicle and venue for quieting title. |
| **2** | **Piercing the Corporate Veil — Single-Member Delaware LLC, Harris County forum.** Please prepare a memo analyzing whether a trade creditor can pierce the veil of a Delaware LLC whose sole member is a Texas-resident individual. The LLC was formed in Delaware in 2019 to operate a single Houston-area restaurant. The sole member routinely paid personal expenses (his home mortgage, his wife's vehicle lease, his children's tuition) directly from the LLC operating account; the LLC never adopted anything beyond a one-page operating agreement, held no member meetings, and was initially capitalized with $5,000 against monthly operating expenses of roughly $80,000. My client, a produce wholesaler, is owed approximately $220,000 on open account. The LLC has ceased operations and is insolvent. Suit will be filed in Harris County. Please address: (1) whether Delaware or Texas law governs the veil-piercing analysis under Texas choice-of-law principles (internal affairs doctrine vs. substantive tort/contract characterization); (2) the substantive standards under each jurisdiction; (3) whether reverse veil-piercing is available; and (4) whether a companion Texas Uniform Fraudulent Transfer Act claim against the individual member is viable and how it interacts with the veil theory. |
| **3** | **Mechanics Lien Priority — Subcontractor vs. Construction Lender, LA County.** Please prepare a memo analyzing priority between my client (an HVAC subcontractor) and a construction lender on a mixed-use project in Los Angeles County. My client first furnished labor and materials on March 3, 2024, and served a 20-day preliminary notice on the owner, general contractor, and the original construction lender on March 28, 2024 (within statutory time). The original lender assigned the construction loan to a successor lender in July 2024; my client did not serve a new preliminary notice on the successor. My client last furnished work on December 15, 2024, and recorded a mechanics lien on February 10, 2025 (56 days later). The general contractor recorded a