Lauyer: An AI Search Tool Built for Portuguese Legal Research

Lauyer is an open-source tool built specifically for Portuguese legal research. It integrates DGSI court judgments and Diário da República legislative resources, supports parallel search and structured output, and is suitable for AI agents and command-line workflows. Its aim is to solve the problem of low retrieval efficiency due to scattered legal information.

When conducting legal research in Portugal, researchers and practitioners often need to switch between multiple platforms such as DGSI (Court Information System) and Diário da República (authoritative legislative source). The scattered information architecture reduces retrieval efficiency and hinders AI agents from automatically acquiring data. Traditional legal databases are mostly designed for web browsing, lacking support for programmatic access and structured output. Integrating them into automated workflows requires dealing with complex scraping or API restrictions, which has spurred the demand for a unified retrieval tool.

Lauyer integrates the DGSI case database and Diário da República regulatory database, using a parallel search architecture to shorten query time. Users can input Portuguese legal terms (e.g., "contrato trabalho" for labor contract) to perform cross-platform searches. Results include titles, summaries, and full texts to ensure information integrity. The tool also provides search optimization suggestions: start with broad terms and gradually narrow down the scope, use professional vocabulary, and add specific law/court names to filter results.

Lauyer supports three output formats: plain text, Markdown, and JSON. The JSON format provides a structured data interface for AI agents (e.g., Claude Code, Codex), enabling them to query the latest court judgments and legislative revisions in real time, avoid relying on outdated training data, improve the accuracy and reliability of AI responses, and support workflows such as automatic case collection and full text retrieval.

Lauyer is suitable for various scenarios: lawyers quickly finding supporting cases for their cases, law students understanding the judicial application of clauses, researchers conducting large-scale case analysis, and AI developers integrating into agents. Practical recommendations: start with a preliminary search using short terms, then refine with precise terms or clause numbers; for complex issues, search related concepts step by step and then synthesize the results. Typical search examples include "pagamento indevido" (unjust enrichment) and "nulidade contrato" (contract invalidity).

Currently, Lauyer supports Windows 10/11 platforms, provides executable files, requires no complex installation, and runs on a command-line interface, making it easy to integrate with scripts and automation tools. Its limitation is that it only covers two sources: DGSI and Diário da República. Future plans include expanding to more Portuguese-speaking region legal databases, supporting EU legislative cases, adding advanced search syntax (Boolean logic, exact matching), and developing a graphical interface to lower the usage threshold.