Symio-ai/legal-research-ranker
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Symio-ai/legal-research-ranker
Model Description
Legal Research Ranker is a cross-encoder reranking model that scores the relevance of legal documents to a research query. Given a (query, document) pair, it produces a relevance score from 0 to 1. Designed to replace generic Cohere Rerank with a legal-domain-specific ranker.
Critical for ensuring the GLACIER pipeline surfaces the most relevant authorities first.
Intended Use
- Primary: Rerank legal research results from CourtListener, Midpage, and bedrock-legal
- Secondary: Score case relevance for precedent matching and brief support
- Integration: Replaces/supplements Cohere Rerank in GLACIER Stage 2
Task Type
text-classification -- Cross-encoder relevance scoring (regression, 0-1 output)
Base Model
cross-encoder/ms-marco-MiniLM-L-12-v2 -- Strong baseline for passage reranking, to be fine-tuned on legal query-document pairs
Training Data
Relevance Scale
- 0.0-0.2: Irrelevant (different topic, jurisdiction, or legal issue)
- 0.2-0.5: Tangentially relevant (same practice area but different issue)
- 0.5-0.7: Relevant (same issue, persuasive authority)
- 0.7-0.9: Highly relevant (same issue, same jurisdiction, similar facts)
- 0.9-1.0: On-point (controlling authority, nearly identical facts)
Benchmark Criteria (90%+ Target)
GLACIER Pipeline Integration
STAGE 2 (Research) --> research-ranker reranks all retrieval results before presentation
STAGE 3 (WDC #1) --> ranker scores supporting authorities for theory strength
STAGE 5 (WDC #2) --> ranker validates that cited authorities are actually the strongest availableTraining Configuration
- Epochs: 3
- Learning rate: 1e-5
- Batch size: 64
- Max sequence length: 512 (query: 64, document: 448)
- Loss: MSE regression loss
- Hardware: AWS SageMaker ml.g5.2xlarge
Limitations
- Optimized for litigation research queries; transactional/regulatory queries may rank lower quality
- Jurisdiction weighting is implicit; a separate jurisdiction filter should be applied first
- Does not understand temporal relevance without explicit signals
- Hard negatives from same practice area are the most challenging failure mode
