AI in Legal Due Diligence: Efficiency Without Autopilot
The use of artificial intelligence in due diligence is still far from settled. As the initial wave of enthusiasm subsides, a more nuanced picture is emerging: while some users continue to raise questions about how much human involvement these tools still require – and whether their benefits justify the cost – others are already reporting significant gains in efficiency.
Despite the lack of consensus, the adoption of artificial intelligence appears almost inevitable. According to a Deloitte survey, 86% of corporations and private equity funds have already incorporated AI tools or advanced data analytics into dealmaking, and 35% are using them in due diligence1.
The question, therefore, is no longer whether AI should be used in legal due diligence, but how to use it, balancing gains in speed and efficiency with the ethical and legal constraints applicable to Brazilian lawyers under the Statute of the Legal Profession and the Brazilian Bar Association (OAB – Ordem de Advogados do Brasil), the OAB Code of Ethics and Discipline, the General Data Protection Law (LGPD – Lei Geral de Proteção de Dados 2), and the Code of Civil Procedure3.
In November 2024, the OAB's Federal Council issued Recommendation 001/2024, setting out guidelines for the use of generative AI in legal practice in Brazil.
In essence, the OAB's guidance focuses on safeguarding data confidentiality and privacy, ensuring the ethical use of AI tools – particularly by preventing unsupervised professional analysis – and fostering a clear understanding of their capabilities and limitations. It also highlights the need for client consent, robust cybersecurity and AI use policies, along with ongoing training and monitoring to ensure compliance.
While the effective use of AI can deliver consistent gains in speed and accuracy, achieving those gains paradoxically requires time, care, and sustained effort. To meet the OAB's recommendations, law firms and legal departments must put in place clear internal policies and processes governing the use of AI in their work.
In due diligence practice, this means clearly defining the scope and boundaries for AI use, developing prompts and agents to map and analyze documents, implementing routines for human review of outputs, and ensuring the continued training of both models and teams.
With these safeguards in place, the use of AI in due diligence can not only shorten review timelines but also enhance the quality of the final output, supporting more efficient and competitive delivery. By automating routine, operational tasks, AI allows professionals to devote more time to higher-value analysis, bringing a sharper, more critical perspective to the strategic issues and genuinely material risks that inform the client's decision-making.
NOTES
1 DELOITTE. Deloitte Survey: GenAI in M&A. New York: Deloitte, October 9, 2025. Available at: www.deloitte.com/us/en/about/press-room/deloitte-survey-genai-in-mna.html.
2 Law 13.709 (August 14, 2018).
3 Law 13.105 (March 16, 2015).
