Decision in Microsoft Copilot Case Helps Define Use of AI in the Courtroom

By Theodore Brown

February 11, 2025

Decision in Microsoft Copilot Case Helps Define Use of AI in the Courtroom

Theodore (Teddy) Brown serves as the Managing Director of Damages at iDS, leading the charge in forensic accounting and commercial damages. Brown transforms complex financial data into insights that empower clients and counsel alike.

The integration of AI in the legal field has prompted both optimism for enhanced efficiency and concerns regarding ethical and procedural reliability. Attorneys and experts are increasingly using tools like ChatGPT, Microsoft Copilot, and various open-source AI models in their work. However, the scope and limitations of these tools, particularly in sensitive areas like expert testimony, remain under scrutiny. The question is when is it appropriate to use AI in the courtroom and in other legal work? 

A recent decision out of New York in a case called “Matter of Weber” offers critical insight into these limitations. In the case, a financial expert’s reliance on AI tools contributed to the disqualification of their testimony. The court assessed allegations of fiduciary breaches by an executor of a trust, with the objecting party (Objectant) presenting a financial expert to evaluate anticipated economic damages. This expert used Microsoft Copilot as a secondary check for his calculations, a decision that ultimately contributed to the judge’s decision to disqualify him. 

Key Judicial Findings 

The financial expert was found unreliable based on the following factors: 

  1. Lack of Standard Practices: The expert admitted he did not employ industry-standard calculations due to cost and time constraints. 
  2. Inadequate Qualifications: The judge deemed the expert unqualified based on deficiencies in his education, training, and familiarity with the relevant calculation methodologies. 
  3. Confusion Over Damage Types: The expert could not clarify if his calculations were for lost profits or capital losses. 
  4. AI-Driven Calculations: Although AI’s use was not the sole basis for disqualification, the judge’s order highlighted concerns over the expert’s reliance on Microsoft Copilot. 

Analysis of the Decision

The judge’s ruling emphasizes that open-sourced AI tools like Microsoft Copilot, are unreliable sources for expert witnesses, primarily because they are not easily verifiable. As I’ll discuss more in a moment, there is a place for closed-source AI tools, which are useful for streamlining tasks, but no AI tool can replace the need for a qualified expert with comprehensive knowledge of their calculations. The use of open-source AI compounded the expert’s other errors, but it was his fundamental lack of qualification that led to his disqualification. 

AI’s Role in Expert Testimony: Benefits and Limitations 

This case highlights the limitations of current, particularly open-sourced AI tools for complex analytical tasks in expert testimony, particularly in high-stakes legal contexts. While closed-source AI can significantly enhance an expert’s workflow, especially in tasks requiring data organization and summarization, it is not yet equipped to replace human judgment in nuanced calculations.

Benefits of Closed-Source AI in Legal Workflows 

Closed-source AI’s capabilities are particularly advantageous for foundational tasks in expert analysis: 

  • Document Indexing: AI can sort and categorize large volumes of documents. 
  • High-Level Summarization: Closed-source AI tools provide summaries, making it easier to understand document contents quickly. 
  • Enhanced Searchability: Closed-source AI enables deep searches in hard-to-index formats like PDFs, images, and videos, adding efficiency and precision. 
  • Timeline Creation: Closed-source AI can streamline the process of constructing timelines, essential in legal analysis and case preparation. 

Read the latest thought leadership and analysis from legal experts

Limitations of Open-Source Tools

However, as demonstrated in Matter of Weber, open-source AI tools like Microsoft Copilot may not reliably perform complex, specialized calculations without oversight. Additionally, no AI should replace an expert’s own understanding and verification of their analytical processes. 

Recommendations for AI Use in Legal Expert Testimony 

  1. Use Closed-Source AI for Preliminary Tasks: Employ closed-source AI for initial data sorting, document summarization, and cross-referencing, rather than primary calculations or critical analysis. 
  2. Ensure Transparency: Experts should be prepared to explain both their methodologies and any AI usage, demonstrating a clear understanding of AI’s limitations. 
  3. Avoid Sole Reliance on AI for Complex Calculations: For higher-level math or domain-specific calculations, experts should prioritize traditional, peer-reviewed methods and apply closed-source AI as a supplemental tool. 
  4. Maintain Qualification Standards: AI cannot compensate for gaps in an expert’s qualifications. Courts continue to rely on the Federal Rules of Evidence to assess an expert’s foundational knowledge, training, education, skill and experience, which remain essential. 

Conclusion 

The matter of Weber underscores that AI, while beneficial, cannot replace fundamental expert qualifications and human judgment. The judicial system, while receptive to AI’s potential, is wary of its limitations. For the legal field, AI represents an advanced tool that, if used correctly, can enhance workflows and efficiencies but must be employed with caution in areas requiring nuanced judgment and specialized knowledge. The use of AI in the courtroom requires especially rigid scrutiny.

As AI technologies evolve, it is essential for legal professionals and experts to stay informed of best practices, ensuring that AI remains a tool that complements, rather than compromises, their expertise.

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