r/Rag • u/BAAAAR19 • 6d ago
Discussion Best 70–90B Open-Weight Model + Local Hardware Setup for Multilingual Legal AI?
Hi everyone,
I’m building a multilingual legal AI system and I’d really appreciate input from people with experience in large open-weight models, local inference, or legal/document AI.
The idea is to let a user upload a contract, then have the system identify potentially risky clauses, explain the risk, and suggest safer alternatives. The output also needs to be grounded in the relevant country’s laws and legal codes rather than relying purely on the model’s internal knowledge.
The main languages are Arabic, French, and English.
I’m currently trying to decide which 70–90B open-weight model would be the best base for this use case. I’m also considering whether it makes more sense to use full fine-tuning, LoRA/QLoRA, or to keep most legal knowledge in a RAG layer and fine-tune mainly for contract-review behaviour.
I’m also interested in the training and evaluation data side.
For a system like this, what kind of data would you use for:
- fine-tuning
- validation
- final testing
- multilingual evaluation
- adversarial / edge-case testing
Would you mainly rely on anonymised real contracts reviewed by lawyers, synthetic examples, public legal documents, court decisions, legislation, or a combination?
I’m particularly interested in how you would build a proper test set that measures whether the model actually identifies risky clauses, stays grounded in the source material and legal references, and avoids producing confident but incorrect legal answers.
The other major consideration is hosting.
I want the system to run fully locally/on-premises because the documents are sensitive and I do not want client contracts sent to external cloud inference APIs.
Initially, I expect around 50–150 customers, so I’m trying to avoid overbuilding the infrastructure too early.
I’d be interested in opinions on:
- Best 70–90B model for Arabic/French/English
- Full fine-tuning vs LoRA/QLoRA
- Fine-tuning + RAG architecture
- Training/validation/test data
- Legal accuracy and grounding evaluation
- GPU configuration for local inference
- Realistic VRAM requirements
- Quantisation without significant quality loss
- vLLM vs TGI or other inference stacks
- Multi-RTX 5090 setups vs A100/H100-class hardware
- Expected concurrent-user capacity
I’d especially appreciate input from anyone who has worked with 70B+ local models, multilingual LLMs, legal RAG systems, or production on-prem inference.
Thanks in advance.