1998 – 2026
The major antitrust actions Microsoft has faced over Windows, Internet Explorer, Office, and the cloud — United States v. Microsoft Corp. in Washington, the parallel Comes class action in Iowa, Sun v. Microsoft, the European Commission's Windows Media Player and server-protocol case, the Internet Explorer browser-choice settlement and the €561 million breach fine, the ongoing Teams unbundling proceeding, and the FTC's smartphone-era successor — the Activision Blizzard merger review.
Sibling page: Windows Versions — release timeline with antitrust-driven changes (Windows XP N, Windows 7 N, the IE browser-ballot screen, the Teams unbundling) called out inline.
Plaintiffs. The United States Department of Justice plus the attorneys general of California, Connecticut, the District of Columbia, Florida, Illinois, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, New Mexico, New York, North Carolina, Ohio, South Carolina, Utah, West Virginia, and Wisconsin. Filed May 18, 1998 in the District of Columbia, before Judge Thomas Penfield Jackson. The state-AG action and the federal action were consolidated for trial.
Theory of liability. Sherman Act § 2 monopoly-maintenance: that Microsoft used its dominant position in Intel-compatible PC operating systems to suppress nascent competition from cross-platform middleware — Netscape Navigator and the Java runtime — by bundling Internet Explorer into Windows 95 and Windows 98 at zero marginal cost, signing exclusionary contracts with OEMs and ISPs, and using its OS distribution to disadvantage rival browsers. A parallel Sherman Act § 1 tying claim alleged Microsoft unlawfully tied IE to Windows.
Trial and findings. The bench trial ran October 1998 through June 1999. Bill Gates's videotaped deposition — portions of which were aired in court — was widely viewed as catastrophic for Microsoft's posture. Judge Jackson issued findings of fact on November 5, 1999 (Microsoft is a monopolist in PC operating systems and exercised that monopoly to harm consumers, competitors, and innovation) and conclusions of law on April 3, 2000 (Microsoft violated §§ 1 and 2 of the Sherman Act).
Breakup remedy and reversal. Final judgment was entered June 7, 2000, ordering Microsoft split into an operating-systems company and an applications company. The D.C. Circuit, sitting en banc, unanimously reversed the breakup remedy on June 28, 2001. The appeals court upheld the § 2 monopoly-maintenance findings but rejected the § 1 tying ruling under the per-se framework, remanded the tying claim for evaluation under the rule-of-reason, and removed Judge Jackson from the case for press contacts during the trial that compromised the appearance of impartiality. The case was reassigned to Judge Colleen Kollar-Kotelly.
Settlement. The Bush DOJ settled with Microsoft on November 2, 2001; nine states and the District of Columbia signed onto the settlement, while California, Connecticut, Florida, Iowa, Kansas, Massachusetts, Minnesota, Utah, and West Virginia held out and continued to seek stronger remedies. Judge Kollar-Kotelly approved the settlement and the parallel state-litigating-states' final judgment on November 1–12, 2002. The consent decree imposed conduct restrictions on Microsoft's OEM contracts, opened communications protocol licensing, and created a Technical Committee with on-site oversight authority.
Decree expiration. The consent decree was originally set to expire in 2007 but was extended in 2006 over Communications Protocol Program compliance failures. Final expiration came on May 12, 2011, ending nearly a decade of court-supervised oversight of Microsoft's contracting and protocol-disclosure conduct.
Why it matters. USA v. Microsoft remains the load-bearing American precedent for platform monopoly cases. It established that bundling can constitute exclusionary conduct under § 2; it set the template for the § 2 case the DOJ later brought against Google (and that Apple is now defending in US v. Apple); and it produced the warning that even a finding of liability does not produce a structural remedy if the appeals process trims aggressive trial-court orders. Every contemporary US tech antitrust case is being argued against this baseline.
Plaintiffs. Joe Comes (an Iowa small-business owner) and a class of Iowa consumers and businesses who bought Microsoft Windows, Office, Word, Excel, or MS-DOS — certified by Polk County District Court Judge Scott Rosenberg in 2005 as a roughly two-million-member class. Filed February 18, 2000, two-and-a-half months after Judge Jackson's findings of fact in the federal case.
Theory of liability. Iowa Competition Law (Iowa Code §§ 553.4–553.5), the state-law analogue to the Sherman Act, plus Iowa consumer-protection claims. The legal theory tracked the federal case: that Microsoft's monopoly-maintenance conduct in PC operating systems and applications inflated prices paid by Iowa consumers and businesses. Iowa was one of the nine "litigating states" that refused to settle in 2001 and continued pressing for broader remedies in parallel with their own state-court actions.
Trial and the document release. Trial began in November 2006 in Des Moines. Plaintiffs' counsel introduced a vast document set drawn from the federal case's exhibit record — tens of thousands of pages of Microsoft internal email, strategy memos, the videotaped Gates deposition, and the “Internet Tidal Wave” memo — under far more permissive Iowa public-record rules than had prevailed in the federal litigation. The Comes exhibits became the canonical public archive of late-1990s Microsoft conduct: the Andreessen-handshake-cancellation emails, the “cut off Netscape's air supply” quote, the early-Java strategy memos, and most of the Gates deposition video first reached the broad public via the Comes trial in 2007.
Settlement. Microsoft and the plaintiff class settled on February 15, 2007, mid-trial, for up to $179.5 million. Iowa class members received vouchers redeemable for software, hardware, or training; unclaimed funds were directed to Iowa public-school technology programs. Microsoft did not admit liability.
Why it matters. Of the dozens of state-court class actions that followed USA v. Microsoft, Comes was both the largest by recovery and the single most important for the public record. The trial's exhibit set is what historians, law professors, antitrust regulators, and journalists have used in every subsequent retelling of the 1990s Microsoft story — including the way Comes-released emails were later cited in the EU Commission's 2004 server-protocol decision and in Bill Gates's own 2017 reflections in Hit Refresh.
Plaintiff. Sun Microsystems, Inc., the developer of the Java programming language and runtime. Filed March 8, 2002 in the Northern District of California, with a parallel suit consolidated before Judge J. Frederick Motz in Baltimore.
Theory of liability. Sherman Act §§ 1 and 2, plus copyright and trade-secret claims. Sun alleged that Microsoft — having failed in its 1996 license to ship a Java-compatible JVM in Internet Explorer — deliberately built a Windows-incompatible Java extension set (J/Direct, J++) and pressured ISVs to use it, splintering Java's "write once, run anywhere" promise. Sun argued this was § 2 monopoly-maintenance conduct (suppressing the cross-platform middleware threat that the federal case had identified) and a separate copyright violation of the original 1996 license.
Procedural posture. Judge Motz issued a preliminary injunction in 2002 ordering Microsoft to ship Sun's Java implementation as part of Windows; the injunction was largely vacated on appeal in 2003. Pretrial motion practice ran into 2004 with the case set for trial.
Settlement. Announced April 2, 2004: Microsoft paid Sun roughly $700 million in antitrust damages, $900 million in patent settlements, and committed to a ten-year patent cross-license and joint technology-collaboration agreement (covering identity management, Java/.NET interoperability, and server-side Windows-Solaris collaboration). Total announced consideration: $1.6 billion. Microsoft also agreed to pay royalty fees for Sun patent rights going forward.
Why it matters. The Java-fragmentation campaign described in the Comes exhibits was the canonical example of the federal case's middleware-suppression theory, and Sun was the only plaintiff with the resources, the standing, and the trial appetite to pursue Microsoft for it directly. The 2004 settlement closed off the cross-platform-Java threat as a litigation surface, and it became the inflection point at which Sun, James Gosling, and the Java leadership pivoted toward open-sourcing the platform — a path that produced OpenJDK in 2007 and, eventually, the Oracle v. Google Java-API copyright fight that ran from 2010 to 2021.
Complainants. Sun Microsystems (server-protocol interoperability) and RealNetworks (Windows Media Player tying). The Commission opened the formal investigation in August 2000 following Sun's December 1998 complaint and consolidated the WMP investigation in 2003.
Theory of liability. Article 82 EC (now Article 102 TFEU) abuse of a dominant position. Two distinct conducts: tying Windows Media Player to Windows in a way that excluded competing media players from achieving meaningful distribution; and refusal to supply the workgroup-server interoperability information that competitors needed to make their server products work with Windows clients on equal terms.
2004 decision. On March 24, 2004 the Commission imposed a €497.2 million fine and ordered two structural remedies: (1) Microsoft must offer a version of Windows without Windows Media Player — the "Windows XP N" SKU later replicated as "Windows 7 N" and on subsequent releases, sold at the same price as the bundled version, an attempt to require unbundling that proved economically ineffective; (2) Microsoft must publish and license, on reasonable terms, the workgroup-server communication protocols that allow non-Microsoft servers to interoperate fully with Windows.
CFI affirmance (2007). The Court of First Instance (now the General Court) affirmed the decision in September 17, 2007, including the fine and both structural remedies. Microsoft did not appeal further.
2008 non-compliance fine. The Commission found Microsoft's protocol-licensing royalty rates unreasonably high and on February 27, 2008 imposed an additional €899 million fine for non-compliance with the 2004 remedy — the largest single antitrust fine the EU had imposed at the time. The General Court reduced the fine to €860 million on June 27, 2012 in case T-167/08.
Why it matters. The 2004 decision established the EU's modern Article 102 enforcement template against platform incumbents: bundling-as-abuse, mandatory interoperability disclosure, and substantial fines reinforced by escalating non-compliance multipliers. That template runs through the Google Shopping decision, the Google Android decision, the 2024 Apple Music Streaming fine, and the DMA's whole gatekeeper framework. The Windows N SKU pattern — ship the bundled version and a stripped version at the same price — also became the EU's preferred remedy shape for tying cases for the next two decades, including (with modifications) the 2024 Teams unbundling action below.
Complainant and origin. Opera Software ASA filed an Article 82 EC complaint against Microsoft in December 2007, arguing that bundling Internet Explorer into Windows replicated the conduct condemned in the US Microsoft case. The European Commission opened a formal investigation in January 2009 and issued a Statement of Objections that month.
Theory of liability. Article 82 EC abuse of a dominant position via tying Internet Explorer to Windows. The Commission's preliminary view was that the practice harmed competition between web browsers, undermined product innovation, and ultimately reduced consumer choice. By the time the case reached the formal-objection stage, Microsoft had largely already lost in the US version of the same claim and the legal posture was unfavorable.
Commitment decision. On December 16, 2009 the Commission accepted Microsoft's binding commitments under Article 9 of Regulation 1/2003. Microsoft agreed to ship a "browser choice screen" via Windows Update to all European-Economic-Area Windows users running Internet Explorer as their default browser. The screen presented a randomized list of the twelve most-popular browsers in Europe and prompted users to install one or more. The commitment ran for five years (through December 2014) on every supported Windows version including Windows 7 and Windows 8.
2013 breach fine. Microsoft shipped Windows 7 Service Pack 1 in February 2011. The choice screen silently disappeared from new SP1 installations and from existing systems updated to SP1, and Microsoft did not detect or correct the omission for fourteen months — affecting roughly 15 million European users. On March 6, 2013 the Commission imposed a €561 million fine on Microsoft for breach of its 2009 commitment, the first such fine in the history of EU antitrust commitment proceedings. Microsoft did not appeal.
Why it matters. The 2009 decision was the moment the browser-choice screen entered EU regulatory practice as a remedy device, a pattern that the Digital Markets Act (Article 6(3)) later codified as a mandatory obligation on every gatekeeper-designated mobile and desktop OS — including Apple's iOS browser-choice screen rolled out in iOS 17.4 in March 2024. The 2013 breach fine was equally important: it set the EU's enforcement expectation that commitment decisions are not soft remedies and that the Commission will fine non-compliance directly rather than reopen an investigation. Both shapes recur in the Teams unbundling proceeding below.
Complainants. Slack Technologies (acquired by Salesforce in 2021) filed the original complaint with the Commission in July 2020, arguing Microsoft had tied Teams to its productivity suites and disadvantaged competing communications platforms. German communications-software vendor Alfaview Corporation filed a follow-on complaint in July 2023. The Commission opened a formal Article 102 investigation on July 27, 2023.
Theory of liability. Article 102 TFEU abuse of dominant position via tying Microsoft Teams to Microsoft 365 and Office 365 productivity suites. The complainants alleged that bundling Teams at zero marginal cost to enterprise customers gave Microsoft a structural distribution advantage that competing communications providers could not overcome on the merits, regardless of product quality — the same shape of claim that Opera had brought against Internet Explorer in 2007.
Microsoft's pre-objection unbundling. Anticipating an adverse Commission decision, Microsoft began offering Microsoft 365 and Office 365 SKUs without Teams to EEA customers in August 2023. In April 2024 Microsoft expanded the unbundling globally, restructuring its commercial SKUs so Teams and the productivity suites could be purchased separately worldwide.
Statement of Objections. On June 25, 2024 the Commission issued a Statement of Objections, formally setting out its preliminary view that Microsoft's bundling between 2019 and 2023 had restricted competition, restricted interoperability between Teams and competitors, and that the post-2023 unbundling alone was insufficient to remedy the harm. Microsoft was given access to the Commission's case file and an opportunity to respond.
Microsoft's response and proposed commitments. Microsoft has acknowledged the Commission's concerns and proposed structural commitments going beyond the 2023–2024 unbundling, including expanded interoperability obligations between Teams and competing communications platforms (data portability for users moving between platforms, embedded-app interoperability with rival providers) and pricing-differential commitments between the with-Teams and without-Teams SKUs. The Commission has been market-testing those commitments with industry stakeholders.
What to watch next. Whether the Commission accepts Microsoft's proposed commitments under Article 9 of Regulation 1/2003 (closing the case without a finding of infringement, the same procedural path as the 2009 IE decision), proceeds to a full prohibition decision with a fine, or rejects the commitments and reopens enforcement. Whether Salesforce/Slack files follow-on private damages actions in EU member-state courts. Whether the case sets a precedent for parallel investigations into tying between Microsoft Copilot and the productivity suites — an emerging concern as enterprise AI becomes the next layer of platform integration.
Plaintiff. The Federal Trade Commission. Microsoft announced its acquisition of Activision Blizzard for $68.7 billion on January 18, 2022, the largest tech acquisition in history at the time. The FTC opened the merger review and on December 8, 2022 filed an administrative complaint in its in-house adjudicative court seeking to block the deal.
Theory of liability. Clayton Act § 7 — that the merger would substantially lessen competition in the markets for high-performance video-game consoles, multi-game-subscription services, and cloud-streaming game services. The FTC's principal concern was that Microsoft would withhold Call of Duty and other Activision Blizzard franchises from Sony's PlayStation, from Nintendo, and from third-party cloud-streaming services in order to advantage Xbox and Game Pass.
PI proceeding (June–July 2023). When the deal's outside date approached and Microsoft signaled it would close, the FTC filed a preliminary-injunction motion in the Northern District of California on June 12, 2023. Judge Jacqueline Scott Corley held a five-day evidentiary hearing and on July 11, 2023 denied the PI, finding the FTC had not shown a likelihood of success on the merits — in particular, that Microsoft's pre-closing commitments to keep Call of Duty on PlayStation for ten years made foreclosure economically unlikely. The Ninth Circuit denied the FTC's motion for an administrative stay on July 14, 2023, and a 9th Circuit panel affirmed the PI denial on the merits in May 2024 (with the FTC having continued the appeal even after the deal closed).
UK CMA parallel review. The UK Competition and Markets Authority blocked the deal on April 26, 2023 over cloud-streaming concerns, becoming the only national regulator to block the merger outright. After Microsoft restructured the deal to divest Activision Blizzard's cloud-streaming rights to Ubisoft (a fifteen-year exclusive license outside the EEA), the CMA cleared the restructured transaction on October 13, 2023, which was also the deal's closing date. The European Commission had earlier cleared the deal in May 2023 with cloud-streaming behavioral commitments.
In-house withdrawal. The FTC's separate Part 3 administrative complaint had been paused while the federal-court appeal ran. On May 22, 2025 the FTC voluntarily withdrew the administrative complaint, ending the case without recovery. The Commission cited the changed enforcement priorities under the new administration and the practical reality that the deal had been closed for nineteen months.
Why it matters. The Microsoft-Activision merger was the most-litigated tech acquisition in history. The FTC's loss in the PI proceeding and at the Ninth Circuit set the limits on the agency's ability to block large vertical mergers on foreclosure theory in the absence of clear pre-closing conduct that demonstrated intent to foreclose. The case also crystallized the divergence between US and UK merger-review approaches to cloud-gaming markets, with the UK CMA proving the most aggressive merger-control authority in the world for tech consolidation through 2023–2024, a posture that flowed directly into the CMA's later Strategic Market Status programme against Apple and Google in 2025–2026.
Microsoft's antitrust history sits in three regulatory regimes that have evolved very differently since 1998. The case rows above are sorted by date of filing; this section flips the view to "everything in country X."
The 1998 federal monopoly-maintenance case (USA v. Microsoft) and its parallel state-court class actions (Comes in Iowa, plus dozens of other state-level settlements not catalogued here), the private antitrust action by Sun (Sun v. Microsoft), and the Activision merger review (FTC v. Microsoft). The federal consent decree expired in 2011 and the FTC's 2025 withdrawal closed the only US Microsoft action active in the last decade.
The Commission has been the most active Microsoft antitrust enforcer since 2004. The Windows Media Player and server-protocol case (€497 million plus a €860 million non-compliance fine), the Internet Explorer browser-choice settlement and the €561 million breach fine in 2013, and the ongoing Teams unbundling investigation opened in 2023. The Windows N SKU and the browser-choice screen are EU-originated remedies still in force on every modern Windows release.
The UK Competition and Markets Authority blocked the original Activision Blizzard transaction in April 2023 over cloud-streaming concerns — the only regulator anywhere to block the deal outright — and cleared the restructured deal in October 2023 after Microsoft divested Activision's cloud-streaming rights to Ubisoft. Discussed in the FTC/Activision row rather than as a separate row because the CMA's intervention is one phase of the same merger.
Comes in Iowa is the canonical entry, but Microsoft settled state-court class actions in California, Florida, Kansas, Massachusetts, Michigan, Minnesota, New Mexico, North Carolina, North Dakota, Ohio, Tennessee, West Virginia, Wisconsin, and the District of Columbia between 2003 and 2007, totaling several billion dollars in voucher and cash recoveries. Most of the released exhibit material on which contemporary historians of 1990s Microsoft draw came from the Iowa proceeding.
The 1998 federal case is the most-taught American antitrust case of the past forty years and the right baseline against which every subsequent platform action is measured. Three things made it consequential. First, the trial record — especially the videotaped Bill Gates deposition and the Andreessen / Allchin internal email set — was the rare modern antitrust case where the documentary evidence was overwhelming and the witness testimony made it worse, not better, for the defendant. Second, the legal theory — that a monopolist's conduct toward nascent threats (Netscape, Java) could constitute exclusionary conduct under § 2 even when the conduct involved giving a product away for free — was a doctrinal advance that the D.C. Circuit affirmed in unanimous en-banc form. Third, the breakup remedy and its appellate reversal taught a generation of antitrust regulators that liability findings and structural remedies are different problems, and that an over-reaching trial court will get its remedy reversed even when its liability findings hold.
The 2001 settlement under the Bush DOJ was widely criticized at the time as too soft. With twenty-five years of hindsight, the more interesting critique is structural: the consent decree's communications-protocol-licensing program, the Technical Committee's on-site oversight, and the OEM contracting restrictions were technically successful at policing the specific conduct identified at trial — and almost entirely ineffective at preventing Microsoft's pivot to the next monopoly surface (online services, Office for the cloud, Azure). The lesson the modern enforcers seem to have absorbed is that conduct-focused remedies expire alongside the conduct they target; structural remedies of the kind Judge Jackson originally ordered would have produced different long-term outcomes, but at the political and judicial cost the appellate process was unwilling to bear.
The case's most cited quotation — that Microsoft's conduct constituted "predacious behavior" toward Netscape — is in fact not from the appellate opinion. It is from Jackson's findings of fact, which the appellate panel pointedly distinguished from his sanctionable press conduct: the findings stand, the press conduct does not. That distinction is the one that lets contemporary courts cite Microsoft while ignoring its political surroundings, and it is why the case anchors the analytical framework in the more recent US v. Apple proceeding even though the politics of that case look very different.
The European Commission's twenty-two-year Microsoft enforcement history is the longest sustained antitrust campaign against a single platform incumbent anywhere in the world. The 2004 WMP-and-server-protocols decision established the template: identify a tying or refusal-to-supply abuse under Article 82, impose a structural remedy (the Windows N SKU, the protocol-disclosure mandate), back it with a substantial fine, and then escalate via non-compliance fines if the remedy is implemented in form but not in substance. The 2008 €899 million non-compliance fine on the same case was the first time the Commission made it explicit that royalty rates set too high to permit competitor adoption are themselves a form of non-compliance.
The 2009 IE browser-choice settlement and the 2013 €561 million breach fine repeated the pattern with a procedural variation. The Commission used Article 9 of Regulation 1/2003 — the commitment-decision route — to close the case without finding infringement, in exchange for binding commitments. When Microsoft then dropped the choice screen from Windows 7 SP1 for fourteen months, the Commission did not reopen the underlying tying case; it fined directly under the 2009 commitment. That is the procedural template the Digital Markets Act now codifies as the default mode of platform regulation: ex-ante obligations, direct fining for non-compliance, no need to relitigate the underlying competition theory each time.
The Teams unbundling proceeding opened in 2023 is the same template applied a third time, twenty years after the WMP decision. Microsoft's pre-Statement-of-Objections unbundling in 2023–2024 was a deliberate echo of its 2004 Windows N response: ship the unbundled SKU early to limit the Commission's remedy options. Whether the Commission accepts Microsoft's commitment proposal or proceeds to a full prohibition decision will turn on whether the post-2023 unbundling addresses the bundling-era harm or merely the going-forward conduct — the same distinction that drove the 2008 protocol-royalty non-compliance fine.
The FTC's loss in the Activision PI hearing was the most consequential merger-review decision against the agency since the Sysco-US Foods case in 2015. Judge Corley's ruling rested on the foreclosure analysis: the FTC had to show that Microsoft would withhold Call of Duty from PlayStation post-acquisition, but Microsoft's pre-closing ten-year licensing commitments to Sony, Nintendo, NVIDIA, and four cloud-streaming providers — each one publicly executed before the PI hearing — effectively answered the foreclosure question on the record. The Ninth Circuit panel that affirmed in 2024 deepened the holding: pre-closing behavioral commitments are admissible evidence on Clayton Act § 7 likelihood of success, even though they fall short of the kind of structural remedy the agency would have demanded had the deal proceeded to a full administrative trial.
The CMA's parallel proceeding produced a different shape of result. The CMA blocked the original deal in April 2023 on the cloud-streaming theory the FTC had largely de-emphasized; Microsoft's response was to restructure the deal to divest cloud-streaming rights to Ubisoft, satisfying the CMA's specific concern without satisfying the FTC's broader foreclosure theory. That divergence — one regulator's narrow concern produces a structural divestiture while another regulator's broader concern produces no remedy at all — became the reference point for the CMA's later move to ex-ante regulation under the DMCC Act 2024 and its 2025 designation of Apple and Google for Strategic Market Status.
The May 2025 FTC withdrawal closed the case formally and left the merger's antitrust file open in a different sense: there is no precedential prohibition decision on Microsoft-Activision under any agency's docket. Future US tech-merger enforcement will have to reason about the case from the PI denial and the 9th Circuit affirmance, not from a final administrative trial result. The doctrinal absence is itself the precedent — the courts have shown what the agency can no longer easily prove, and the agency has shown it will not waste resources litigating a closed deal whose theory courts have rejected.
The 1998 federal case is the doctrinal taproot of every contemporary US tech-platform antitrust action. Its § 2 monopoly-maintenance theory is the legal scaffolding of US v. Google (the search case decided August 2024) and the DOJ smartphone case against Apple. Its remedial cautionary tale — aggressive trial-court remedies reversed on appeal — is the constraint Judge Mehta is actively reasoning about in Google's remedies phase. The findings-of-fact / conclusions-of-law procedural sequence Microsoft pioneered is now the standard structure for federal antitrust bench trials.
The EU Microsoft cases shape the DMA in even more direct ways. The Windows N SKU is the structural ancestor of every "ship a stripped version alongside the bundled version" remedy the Commission has imposed since. The 2009 browser-choice screen is the direct ancestor of the DMA's Article 6(3) browser-choice obligation, which Apple implemented in iOS 17.4 in March 2024 and which Microsoft itself implemented for the EU Edge default in Windows 11 24H2 around the same time. The 2013 €561 million breach fine is the procedural ancestor of the April 2025 €500 million DMA non-compliance fine on Apple: directly fined under a binding obligation rather than relitigated under a fresh competition theory.
The Activision merger review's lesson runs the other direction: it shows the limits of US vertical-merger enforcement, which is why the most aggressive contemporary merger enforcement is happening in the UK rather than the US. Every active platform-distribution regulatory action in 2026 — CMA SMS designation for Apple and Google, Teams unbundling, the EU DMA non-compliance procedures — sits within the framework these Microsoft cases established a generation ago.
Patent disputes between Microsoft and other companies (e.g. the Eolas web-browser plug-in patent litigation, the Motorola standard-essential-patent fight, the i4i XML-formatting case) are not antitrust cases and do not appear here. They are part of Microsoft's general litigation history, not the antitrust record.
State-court class actions other than Comes — the California, Florida, Minnesota, and other state-level Microsoft consumer settlements — tracked the 1998 federal case's theory and resolved on similar voucher-plus-cash terms. Comes is on the page as the canonical entry because it is the largest by recovery and the source of the public exhibit archive; the others are catalogued in the federal-state-litigation record and do not warrant individual rows here.
Private commercial-relationship disputes (Be Inc. v. Microsoft, Burst.com v. Microsoft, and the long stream of vendor disputes that settled with confidential payments through the 2000s) tracked specific commercial-conduct theories rather than the broader monopoly-maintenance pattern and are out of scope for this page.
Cloud-services antitrust matters — the recurring complaints from European cloud-services trade associations over Microsoft's licensing terms for running its software on rival cloud platforms (AWS, Google Cloud) — have produced settlements with CISPE in July 2024 and reorganized commercial-licensing practices, but no formal Commission decision yet. If a formal investigation opens, the right home is a new row on this page.
Predictions about case outcomes. Until a ruling, settlement, or judgment lands, the page reports the procedural posture without forecasting where the case is headed. Editorial framing ("Microsoft was right / wrong"; "the ruling was correct / incorrect") is also out of scope.
The links below point to the authoritative places to read the dockets and rulings directly — news coverage is downstream of these primary sources.
All four are in DC, California, or before the FTC; CourtListener mirrors most filings.
# Free Law Project (CourtListener) docket mirror
https://www.courtlistener.com/ # search: "United States Microsoft" (D.D.C. 1998)
https://www.courtlistener.com/ # search: "FTC Microsoft" (N.D. Cal. 2023)
# DOJ Antitrust Division — consent decree archive
https://www.justice.gov/atr/case/us-v-microsoft-corporation
# D.C. Circuit en-banc opinion (June 28, 2001)
https://www.cadc.uscourts.gov/ # 253 F.3d 34
# FTC In re Microsoft/Activision — matter 2210077
https://www.ftc.gov/legal-library/browse/cases-proceedings/2210077-microsoftactivision-blizzard-matterThe Iowa-released exhibit set is the canonical public archive of the 1998 federal trial's documentary record.
# Comes v. Microsoft exhibits (Groklaw mirror, archived)
https://web.archive.org/web/*/groklaw.net/staticpages/index.php?page=ComesvMS
# Internet Archive Wayback Machine
https://web.archive.org/ # search the iowaconsumercase.org domainAll three Microsoft EU cases are managed by DG Competition; appeals run at the General Court in Luxembourg.
# Case COMP/C-3/37.792 — 2004 WMP and server-protocols decision
https://competition-cases.ec.europa.eu/cases/COMP_C_3_37792
# Case COMP/39.530 — 2009 Internet Explorer commitment decision
https://competition-cases.ec.europa.eu/cases/COMP_39530
# Case AT.40873 — 2023 Teams unbundling investigation
https://competition-cases.ec.europa.eu/cases/AT.40873
# EU General Court (appeals)
https://curia.europa.eu/
# DG Competition press releases
https://ec.europa.eu/commission/presscorner/api/newsThe CMA's full final report and the restructured-deal decision are on gov.uk.
# Microsoft / Activision Blizzard merger inquiry
https://www.gov.uk/cma-cases/microsoft-slash-activision-blizzard-merger-inquiry
# Restructured-deal decision (October 13, 2023)
https://www.gov.uk/cma-cases/microsoft-slash-activision-blizzard-restructured-dealSources: United States v. Microsoft Corp. D.D.C. and D.C. Cir. dockets and the en-banc opinion at 253 F.3d 34 (D.C. Cir. 2001); Comes v. Microsoft Corp. Polk County Iowa District Court docket and exhibit archive (mirrored on Internet Archive); Sun Microsystems, Inc. v. Microsoft Corp. N.D. Cal. and consolidated D. Md. dockets and the April 2, 2004 settlement announcement; European Commission decisions COMP/C-3/37.792 (2004 WMP and server protocols), COMP/39.530 (2009 Internet Explorer commitment, 2013 breach fine), and AT.40873 (2023 Teams investigation, June 2024 Statement of Objections); Court of First Instance opinion T-201/04 (Sept 17, 2007) and General Court opinion T-167/08 (June 27, 2012); FTC v. Microsoft Corp. N.D. Cal. 23-cv-02880 docket, 9th Circuit 23-15992 docket, FTC Part 3 administrative matter 2210077, and the May 22, 2025 FTC withdrawal notice; UK CMA Microsoft/Activision Blizzard merger-inquiry final report (April 26, 2023) and restructured-deal decision (October 13, 2023); CourtListener (Free Law Project) docket mirrors; contemporaneous reporting in Reuters, Bloomberg, NYT, WSJ, The Information, FT, and Politico Europe. Court records, EU Commission decisions, and UK CMA reports are public; reporter coverage is cited under fair use (linked, not republished). Last updated April 2026.
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