AI Semantic Search · NLP · Vector Retrieval

AI-Powered Semantic Search Tool

We built a production-grade semantic search engine for a legal-tech firm, using modern NLP and vector search to surface contextually relevant cases—not just keyword matches. The engine understands legal language, intents, and relationships between documents, helping lawyers and researchers get to the right precedents in a fraction of the time.

Powered by BERT-family sentence embeddings, vector databases, and a robust Python API layer, the platform analyzes 10K+ legal documents and continuously improves as new data and feedback come in.

Recommendation accuracy

≈ 90%

Top-5 semantic matches vs. manually curated case references.

Research time

−65%

Average time saved per query in legal research workflows.

Corpus size

10K+

Judgements, case laws, and internal knowledge documents.

Integration

API-first

Custom REST APIs integrated with the client’s existing CMS.

Legal-tech semantic search case study

From keyword search to context-aware discovery

Traditional keyword search falls short in legal research where synonyms, nuanced phrasing, and cross-case references matter. We replaced simple text search with true semantic retrieval, tuned specifically for legal language and workflows.

The challenge
  • Keyword-based search missed relevant cases when phrasing or terminology differed.
  • Lawyers manually sifted through dozens of results with near-duplicate or irrelevant cases.
  • No ranking mechanism based on semantic relevance, citation strength, or outcome similarity.
  • Existing CMS had limited support for AI features or advanced search operators.
Our solution
  • Deployed a BERT-based sentence embedding model (via Hugging Face Transformers) for semantic understanding.
  • Built a vector search layer on top of a dedicated vector database / dense index for fast ANN queries.
  • Wrapped the engine in a Python FastAPI microservice, exposing REST endpoints for search and re-ranking.
  • Integrated seamlessly into the client’s CMS via custom APIs and UI widgets for lawyers and analysts.
Business outcome
  • Lawyers now receive fewer but more relevant case recommendations for each query.
  • Junior staff can perform research at near-senior quality levels with AI-assisted suggestions.
  • Research time was reduced by ~65%, freeing teams to focus on strategy and argumentation.
  • The semantic engine became a reusable AI layer that can be extended to contracts, FAQs, and internal docs.
Architecture & AI stack

How the semantic search engine works under the hood

The platform combines modern NLP models, vector search, and a robust backend layer to deliver low-latency, high-quality recommendations integrated with the client’s existing tools.

End-to-end AI pipeline
1. Ingestion & preprocessing

Legal documents (PDF, Word, HTML, CMS entries) are ingested via ETL jobs. Text is cleaned, segmented into passages, and enriched with metadata (court, jurisdiction, topics, citations).

2. Embedding generation

A BERT-based or SentenceTransformer model encodes each passage into dense vectors. Batch jobs run on GPU-enabled workers, and embeddings are versioned to support model upgrades without downtime.

3. Vector indexing & storage

Embeddings are stored in a vector database / ANN index (e.g., Elasticsearch/OpenSearch with vector fields, or dedicated vector DB). Metadata stays in PostgreSQL / document storage, linked by stable IDs.

4. Query understanding & retrieval

User queries are encoded into vectors in real time. The engine performs top-K vector search, then optionally re-ranks with a cross-encoder or scoring function tuned for legal relevance and citation strength.

5. API layer & CMS integration

A FastAPI-based microservice exposes search endpoints, suggestion APIs, and analytic hooks. The client’s CMS calls these APIs to show recommended cases, related judgements, and “similar documents” widgets.

Core AI & NLP stack
Python · FastAPI Hugging Face Transformers BERT / SentenceTransformers PyTorch / TensorFlow (depending on model)
Search & data layer
Vector DB / ANN index (e.g., Elasticsearch/OpenSearch) PostgreSQL for metadata & audit logs Redis for caching hot queries
Pipelines & reliability
Celery / RQ for batch embedding jobs Scheduled re-index & drift monitoring Dockerized services for deployment
MLOps & observability
Metrics on latency, recall@K, and usage Model/version registry for safe rollouts Role-based access to AI endpoints