UK tribunal greenlights Microsoft licensing suit

A UK tribunal has cleared a £1.7 billion class action accusing Microsoft of overcharging organizations that ran Windows Server on rival clouds instead of Azure. (catribunal.org.uk) (money.usnews.com) The Competition Appeal Tribunal said on April 21 that Dr. Maria Luisa Stasi’s claim can proceed as opt-out collective proceedings, covering UK-domiciled organizations that bought Windows Server licenses from listed providers. The tribunal’s case page says the claim was registered on December 3, 2024, heard in December 2025, and certified on April 21, 2026. (catribunal.org.uk) The proposed class covers about 59,000 to 60,000 businesses and other organizations, and the damages estimate is roughly £1.7 billion, or about $2.8 billion. The claim says Microsoft charged more to use Windows Server on Amazon Web Services, Google Cloud and Alibaba Cloud than on Azure. (theregister.com) (money.usnews.com) Windows Server is the software many companies use to run core business systems, and cloud providers rent the computing power underneath it. The lawsuit turns on whether Microsoft’s license terms made the same software costlier on competing clouds, even when the underlying computing service came from someone else. (computerweekly.com) (catribunal.org.uk) The legal theory is abuse of dominance under the UK Competition Act 1998 and Article 102 of the Treaty on the Functioning of the European Union. The claim says Microsoft used its strength in server software to steer customers toward Azure through licensing terms rather than lower infrastructure prices alone. (catribunal.org.uk) (oeclaw.co.uk) That fight has been building beyond this case. Ofcom’s October 2023 cloud market study said cloud computing had become essential infrastructure for UK businesses and referred the sector to the Competition and Markets Authority for deeper investigation. (ofcom.org.uk) (gov.uk) UK competition authorities later said Microsoft’s licensing practices were hurting the ability of Amazon Web Services and Google to compete for customers that use Microsoft software in the cloud. In the regulator’s summary of its final decision, Microsoft’s licensing was singled out alongside other barriers such as technical switching costs. (gov.uk) Microsoft disputes the case. The company said it contests the underlying allegations and that certification does not amount to a finding that it broke competition law; reports on the ruling said Microsoft plans to appeal. (finance.yahoo.com) (money.usnews.com) Microsoft has also tried to resolve similar pressure elsewhere. In July 2024, it settled a complaint from Cloud Infrastructure Services Providers in Europe, agreeing to product changes and a €20 million payment, while rivals said the broader licensing dispute was not over. (cispe.cloud) (datacenterdynamics.com) The UK case now moves from the question of whether it can be brought to the question of whether Microsoft’s pricing actually harmed customers. For thousands of organizations that buy Microsoft software and third-party cloud capacity together, that is the bill the tribunal will test next. (catribunal.org.uk) (theregister.com)