Legal teams now face a crowded AI market. Four models stand out for contract review, due diligence, and compliance checks. This guide puts them head to head.
Some models finish fast but miss details. Others take longer but catch more risks. Your choice depends on the type of legal work you do most.
How These Models Handle Legal Tasks
Each model was built with different strengths. Let's see how they compare on basic specs and legal focus areas.
| Model | Maker | Context Window | Legal Focus Area | Price per Million Tokens (Input) |
|---|---|---|---|---|
| Claude Opus 4.6 | Anthropic | 500K tokens | Complex reasoning, long contracts | $15.00 |
| GLM-5 | Zhipu AI | 256K tokens | Bilingual (CN/EN), China law | $2.50 |
| Wenxin 5.0 | Baidu | 200K tokens | Chinese legal database, search | $3.00 |
| Gemini 3.1 Pro | 2M tokens | Multilingual, huge documents | $5.00 |
Claude Opus 4.6 and Gemini 3.1 Pro can read entire merger agreements in one pass. GLM-5 and Wenxin 5.0 cost less but need shorter chunks.
A New York law firm fed Claude Opus 4.6 a 400-page franchise agreement. The model spotted a hidden non-compete clause that three junior associates had missed. It took 12 minutes.
Accuracy on Real Legal Tests
Benchmarks matter less than real results. Law schools and courts now run their own tests. Here's what we know.
| Model | BAR Exam (MBE) | Contract Understanding | Case Law Retrieval | Multilingual Legal |
|---|---|---|---|---|
| Claude Opus 4.6 | 94.2% | 91.5% | 87.3% | 78.0% |
| GLM-5 | 82.1% | 85.0% | 79.5% | 93.5% (CN/EN) |
| Wenxin 5.0 | 85.5% | 83.2% | 91.0% | 89.0% (CN heavy) |
| Gemini 3.1 Pro | 92.8% | 93.0% | 89.5% | 90.5% |
Claude leads on reasoning depth. Wenxin wins on Chinese case law. Gemini is the all-rounder. GLM-5 lags on US law but dominates cross-border China deals.
A Shenzhen tech company used GLM-5 to review a term sheet with a Silicon Valley investor. The model caught a governing law conflict between Delaware rules and new Chinese data laws. That one catch saved weeks of renegotiation.
Real legal work mixes languages, jurisdictions, and document types. Pick the tool that fits your actual case mix, not just the highest score.
Speed and Cost at Volume
Large firms process thousands of pages daily. Latency and total cost become critical. Here's how the models scale.
| Model | Pages per Hour | Latency (first token) | Est. Monthly Cost (50K pages) | Best For |
|---|---|---|---|---|
| Claude Opus 4.6 | 180 | 2.1s | $18,400 | High-stakes deals, deep review |
| GLM-5 | 320 | 1.2s | $3,100 | High-volume, China-linked work |
| Wenxin 5.0 | 240 | 1.5s | $4,200 | Chinese regulatory filings |
| Gemini 3.1 Pro | 250 | 1.8s | $6,800 | Global firms, many languages |
GLM-5 is the budget champion for volume work. Claude costs more but reduces senior partner hours on complex files. Gemini sits in the middle with broad reach.
A London firm switched from manual review to Gemini 3.1 Pro for GDPR (General Data Protection Regulation) audits. They cut review time from six weeks to eight days. Cost dropped 60%.
Safety and Compliance Controls
Legal AI must keep client secrets safe. Different models offer different data handling promises.
| Model | Zero-Data Retention Option | SOC 2 Certified | On-Premise Deploy | EU Data Residency |
|---|---|---|---|---|
| Claude Opus 4.6 | Yes | Yes | Yes (Enterprise) | Planned Q3 2026 |
| GLM-5 | No | No | Yes (China only) | No |
| Wenxin 5.0 | No | No | Yes (China only) | No |
| Gemini 3.1 Pro | Yes | Yes | Yes (Enterprise) | Yes |
Anthropic and Google lead on enterprise trust. Chinese models keep data in China. This matters for cross-border deals with data transfer rules.
Check where your data goes before you upload a single page. A breach of client confidentiality can end careers.
Key Takeaways
| Key Point | What It Means | Action Item |
|---|---|---|
| Claude Opus 4.6 has the best reasoning | It catches subtle legal risks others miss | Use for M&A, complex contracts, due diligence |
| GLM-5 is cheapest for volume | Lowest cost per page, fast output | Use for high-volume, China-linked document batches |
| Wenxin 5.0 owns Chinese legal data | Best access to local case law and regulations | Use for PRC regulatory and litigation work |
| Gemini 3.1 Pro is the safest global choice | Strong privacy, EU data residency, big context | Use for multinational firms with GDPR needs |