The Federal Circuit's March 6, 2026 decision in Exafer Ltd. v. Microsoft Corp. establishes that courts cannot use Daubert standards as a shortcut to eliminate patent damages theories simply because they rely on unaccused royalty bases. This ruling has immediate implications for Microsoft's ongoing patent litigation strategy and could reshape how technology companies defend against infringement claims.

At the heart of the case was whether patent holders can base damages calculations on royalty rates from products not specifically accused of infringement. Microsoft argued that such calculations should be automatically excluded under Daubert and Federal Rule of Evidence 702, which govern the admissibility of expert testimony. The company sought what legal observers called a "per se bar"—an automatic exclusion without case-specific analysis.

Judge Timothy Dyk, writing for the Federal Circuit panel, rejected this approach. "Daubert does not create a shortcut to wipe out patent damages theories simply because they rely on unaccused royalty bases," the court stated. Instead, judges must conduct the traditional Daubert analysis, examining whether the methodology is reliable and properly applied to the facts of each case.

Microsoft's Litigation Context

This decision comes as Microsoft faces increasing patent litigation related to its cloud computing services. The company's Azure platform, Windows Server products, and enterprise software suites have become frequent targets for patent assertion entities and competitors. Microsoft has historically employed aggressive Daubert challenges to limit damages exposure, particularly in cases involving complex technology where damages calculations can vary widely.

Legal analysts note that Microsoft's strategy has often focused on narrowing the damages base to specific accused products rather than allowing plaintiffs to use broader market comparisons. The Federal Circuit's rejection of a per se rule against unaccused royalty bases removes one of Microsoft's preferred tools for early-stage litigation defense.

Technical Implications for Cloud Computing

The Exafer case specifically involves cloud computing technology, though the Federal Circuit's ruling applies broadly to all patent litigation. For Microsoft's Azure services, this means patent holders may now have greater flexibility in how they calculate damages for alleged infringement.

Cloud computing presents unique challenges for patent damages calculations. Services like Azure involve complex, interconnected systems where specific components might be accused of infringement while others are not. The Federal Circuit's decision acknowledges that in such integrated systems, royalty bases from related but unaccused products might provide relevant comparables for damages calculations.

Practical Impact on Patent Litigation

Patent attorneys immediately recognized the decision's significance. "This ruling forces defendants to engage with the substance of damages methodologies rather than seeking automatic exclusions," said one intellectual property litigator familiar with Microsoft's cases. "For Microsoft, this means more detailed, case-specific challenges rather than blanket motions."

The decision also affects how expert witnesses prepare damages reports. Experts can now more confidently include analyses based on comparable products and technologies, knowing that such approaches won't be automatically excluded. However, the Federal Circuit emphasized that this doesn't mean all such analyses will be admissible—only that they must be evaluated under traditional Daubert standards.

Microsoft's Response and Strategy Adjustments

Microsoft has not publicly commented on the decision, but legal observers expect the company to adjust its litigation approach. The software giant will likely focus more on challenging the specific application of damages methodologies rather than seeking categorical exclusions.

This shift could lead to more extensive discovery battles over damages-related documents and more detailed expert reports. For Microsoft's in-house legal team, this means allocating additional resources to damages-related litigation phases rather than relying on early Daubert wins.

Broader Industry Implications

The Federal Circuit's decision affects not just Microsoft but the entire technology sector. Companies like Amazon, Google, and Oracle face similar patent challenges related to their cloud services and enterprise software. All will now operate under the same standard when defending against damages calculations based on unaccused products.

For patent assertion entities, the ruling provides more flexibility in how they structure damages theories. This could potentially lead to higher settlement demands in some cases, though the Federal Circuit emphasized that reliability standards remain high.

The Daubert Standard in Patent Cases

Daubert challenges have become increasingly common in patent litigation, particularly in technology cases where damages calculations can reach hundreds of millions of dollars. The standard requires judges to act as gatekeepers, ensuring that expert testimony is based on reliable methodology and properly applied to the facts.

Microsoft has been particularly active in filing Daubert motions in patent cases. The company's legal team has developed sophisticated arguments about what constitutes reliable damages methodology in complex technology markets. The Exafer decision doesn't eliminate these arguments but requires they be made on a case-by-case basis rather than as categorical rules.

Looking Forward: Next Steps in the Exafer Case

The Federal Circuit's decision remands the case to the district court for further proceedings consistent with the opinion. This means the trial court must now conduct a proper Daubert analysis of Exafer's damages theories rather than excluding them automatically.

For Microsoft, this extends the litigation timeline and increases costs. The company must now prepare detailed challenges to Exafer's specific methodologies rather than relying on a broader legal argument. This could involve additional expert reports, depositions, and briefing focused specifically on damages issues.

Strategic Considerations for Technology Companies

Technology companies facing patent litigation should review their Daubert strategies in light of this decision. The automatic exclusion of damages theories based on unaccused products is no longer available. Instead, companies must prepare more nuanced challenges that address the specific reliability concerns in each case.

This may require earlier engagement with damages experts during case preparation and more detailed analysis of plaintiffs' damages methodologies. For in-house counsel at Microsoft and other tech firms, this decision adds complexity to litigation planning and resource allocation.

The Patent Damages Landscape

Patent damages have become increasingly contentious in recent years, with courts struggling to apply traditional damages principles to modern technology markets. The Federal Circuit has issued several important decisions refining how damages should be calculated in patent cases, particularly for complex products and services.

The Exafer decision fits within this broader trend of rejecting bright-line rules in favor of case-specific analysis. This approach recognizes that technology markets vary widely and that flexible standards are necessary to ensure fair compensation while preventing excessive damages awards.

For Microsoft, this means continued uncertainty in how damages will be calculated in future patent cases. The company cannot rely on categorical rules to limit damages exposure but must instead engage in detailed, fact-intensive litigation over damages methodologies.

Conclusion

The Federal Circuit's rejection of Microsoft's per se bar argument represents a significant development in patent litigation strategy. While the decision doesn't guarantee that damages theories based on unaccused products will be admitted, it requires courts to evaluate them under traditional reliability standards rather than excluding them automatically.

For Microsoft's ongoing and future patent litigation, this means more complex and resource-intensive damages phases. The company's legal team must now prepare for detailed battles over damages methodologies rather than seeking early wins through categorical exclusions.

The decision also has broader implications for the technology industry, where integrated products and services make damages calculations particularly challenging. All companies facing patent claims will need to adjust their litigation strategies to account for this more nuanced approach to Daubert challenges.

As patent litigation continues to evolve in response to new technologies and market realities, decisions like Exafer v. Microsoft will shape how courts balance the rights of patent holders against the need for predictable and reasonable damages calculations. For now, Microsoft and other technology defendants have lost one tool in their litigation arsenal but gained clarity on how future challenges must be structured.