It is generally agreed that Microsoft stole parts if not entire blocks of intellectual property from Digital Research, Xerox, Apple, and several other major corporations.

To keep it simple, lets stipulate for MS actions prior to 1995 (Though they may have been sued for their pre-1995 actions at a later date).

Did any major corporation ever successfully sue Microsoft for intellectual property theft?

  • 9
    I have to disagree with the premise of the question. Microsoft copied ideas from other companies, but as a matter of law general ideas are not intellectual property, no matter what Apple says. Only specific implementations are protected, whether via patent or copyright. You can protect your mousetrap, you can't protect the concept of catching mice, which is what Apple claimed. Jan 31, 2018 at 22:14
  • 2
    @fluffysheap actually, I think the Apple case failed only because the relevant property had been licenced. Apple thought only for Windows 1.0 but the court found that a proper reading of the context stated otherwise. Though that's slightly academic — licencing also definitely isn't theft! Though try getting that point across next time somebody whines about Xerox and Apple.
    – Tommy
    Jan 31, 2018 at 22:24
  • 1
    1) Microsoft copied lots of ideas (both Microsoft and Apple got ideas from Xerox PARC, and the Xerox engineers, as I recall, were happy to show them off for someone to use since Xerox wasn't particularly interested), and innovated others.
    – Dranon
    Jan 31, 2018 at 23:15
  • 2
    @Tommy: Actually, in the Xerox vs. Apple case, it was not licensed. Xerox's case was partly thrown out on rather strange legal grounds. Xerox mostly asked for a declaratory judgement to prevent Apple from suing Xerox (or their licensees). It was thrown out because the court (claimed it) wasn't convinced that Apple was likely to file such a case. The rest stemmed from Xerox basically wanting patent-like protection, but there being no patents on software at the time. If it were happening today, and Xerox's patent attorneys were good at all, they'd almost certainly win easily. Feb 1, 2018 at 0:36
  • 4
    Apple had a much stronger case that Microsoft stole code from QuickTime for Windows than the look and feel case that Apple lost. Microsoft agreed to write Mac Office for 5 years and paid Apple $150m in 1997 to make the QuickTime lawsuit go away en.wikipedia.org/wiki/San_Francisco_Canyon_Company Feb 2, 2018 at 17:31

2 Answers 2


Alcatel-Lucent won a lawsuit against MS in 2008 on a patent for audio file playback. That was later overruled by a higher court.

Bristol Technology attacked MS for not revealing needed Windows sources and entering other markets. MS was charged to pay $1M to Bristol in 2000.

Spyglass, the company that originally built what is Internet Explorer today, filed a case against MS on the basis that MS was giving their product away for free after they licensed it from them, inhibiting them from making any money and won $8M (which I would consider a ridiculously low sum today - apparently, internet wasn't considered important by that court at that time).

Stac was already mentioned in another answer

Sun Microsystems were successful in court in forcing MS stop shipping their own "MS standard" Java VM, probably the only company that successfully attacked MS's traditional way of working with open industry standards (pretend to adopt, change in an incompatible way, take over, make your own version).

There were numerous lawsuits other than that in MS history, obviously. MS policy has apparently always been to settle such lawsuits in private agreements outside court.

Most of those (except the first, which MS won in the long run) were not directly on theft of IP, but rather improper usage of IP or "predatory business practices". I personally think IP theft is so hard to prove, (especially has been in the early days, and see SCO vs. Linux) that lawyers will likely revert to other means to get at someone if they can. Most of the accusals of IP theft MS decided to settle outside court, probably to cover the details.

  • 3
    You've characterized the Sun vs. MS lawsuit almost exactly the opposite of reality. Microsoft didn't make any incompatible changes at all--Sun was the one that made a change that wasn't backward compatible. The lawsuit was only over the terms of the contract. The court ruled that the contract allowed Sun to make any such changes they wanted, as often as they wanted, and require Microsoft to follow them or quit shipping a JVM. In short, no matter how hard Microsoft might try to follow the contract, Sun was in a position to prevent them from doing so. Feb 1, 2018 at 21:30
  • 3
    At the time, Sun was also allowing other JVM licensees to continue shipping their implementations of the older standard, just like Microsoft was doing, so it was fairly clearly a direct attack on Microsoft, not just trying to enforce following the new standard. In short, far from being "Microsoft doing bad things", this was Sun using Microsoft to popularize Java, then when that worked, turning around and stabbing their former partner in the back. Feb 1, 2018 at 21:32
  • 3
    @tofro: Think about what you just quoted for a moment. This really translates to Sun saying: "Microsoft wrote a better JVM than ours, so Java on Windows worked better than Java on other platforms." (Oh, and yeah, that's exactly how it was, too). I had the joy of testing the "wrote once, run anywhere" motto a bit early on. Getting an applet to work on just three OSes (Solaris, Windows, and Mac OS) made porting C code seem like a breeze by comparison. Feb 1, 2018 at 21:41
  • 3
    The real reason Sun was angry came down to one thing: Sun thought they'd rigged the game so they could win. Then Microsoft came in and played Sun's game by Sun's rules--and even then, made Sun's work look utterly sad by comparison. Feb 2, 2018 at 15:42
  • 2
    "pretend to adopt, change in an incompatible way, take over, make your own version" - This is usually referred to as EEE (Embrace, Extend, Extinguish). Feb 7, 2018 at 13:27

Stac Electronics obtained a 1994 judgment against Microsoft for patent infringement, based on Microsoft's use of knowledge it had learnt from Stac's source code for Stacker, which it had obtained while considering a purchase of the company, during implementation of DoubleSpace.

Microsoft filed an appeal but Stac one-upped them with a successful injunction on sales of affected copies of DOS, so Microsoft ended up settling. So Stac's action was a success.

Stac had IPOd in 1992, selling 3 million shares at "a a respectable" $12/share (though it quickly dropped). Given Stacker's profile at the time and the respectable IPO, I would argue that the company meets the appropriate definition of a 'major corporation', albeit that it wasn't a Xerox or Apple as I'm willing to wager that's more value than was contemporaneously assigned to Digital Research.

  • 2
    Good point. I had forgotten about this. When I ask the question, it seemed to me somebody successfully sued MS for some type of audio technology too. I remember MS hiring employees from other companies that may have brought illegal software with them, but I can't remember any specific cases - perhaps Borland and one or more of their compilers as an example.
    – jwzumwalt
    Feb 1, 2018 at 6:43
  • Didn’t MS pay the fine / damages the a few days later bought the company anyway...
    – Solar Mike
    Feb 2, 2018 at 13:26
  • I can't find a reliable (i.e. not Wikipedia) source for what happened next, but Wikipedia thinks Stac used the payment and subsequent royalties to try to move into remote desktop access, spun off a chip subsidiary and took a shot at providing more general remote support software, then eventually realised that things weren't going well so sold the assets and returned the resulting money to its shareholders, much like Michael Dell once advised Apple.
    – Tommy
    Feb 2, 2018 at 17:30
  • @jwzumwalt I think it stuck in the memory only due to the abrupt renaming of DoubleSpace as DriveSpace.
    – Tommy
    Feb 2, 2018 at 17:31
  • 1
    Based on what I recall, the patent infringement was related to a defragging like operation, not the initial compression of files. The compression algorithm is based on Lempel-Ziv's 1977 "moving window" compression scheme. The patent doesn't change the original scheme, and only covers specifics like the hashing used to speed up searches for prior strings in the moving window and the Huffman tree used to encode the compressed data. Microsoft released MSDOS 6.22 with a minor change sufficient enough to not violate the specifics of the patent.
    – rcgldr
    Mar 29, 2019 at 7:19

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .