I have purchased a software product, which the company claims is licensed to me, and it contains an EULA that says that I am not allowed to reverse engineer or modify the software at all, and a violation of this would allow them to revoke my license.

Now, I'm an experienced software developer who has built a business around using said software product. I rely on it, and have done so for over 15 years now. Losing access to it would be a serious blow to my business, hence I like to avoid losing the license, of course.

More than once in the past it has happened that I run into programming errors of said product, hindering my ability to use it as intended. And while the software lives up to its expectations in general (i.e. I cannot claim that it's useless to me), certain bugs limit its provided and documented functionality.

Now, being an experienced developer, I am usually able to figure out the cause of the error by just observing how it behaves. And while I am often able to "work around" the bugs, sometimes the only way to solve the issue is to modify the product's code or interfere with it in some way that requires me to look at the code, i.e. reverse engineer parts of it. (Note: The code in question is not encrypted nor protected in some other way.)

By doing that, the company claims I am in clear violation of their EULA.

I initially argued that the purpose of their "no reverse engineering" rule is to prevent harmful hacks, such as trying to disable their product registration and copy protection, and the company agrees with that. However, they argue they cannot make exceptions to their rule at all (which I believe they confuse with enforcing trade mark violations, where too much leniency could make them lose the rights to their claims).

Which leaves me almost no options:

  • I am not allowed to fix their bugs myself, even if only for my own use of the software.

  • Neither are they willing (or able) to fix them.

  • Which leaves me only able to simply not use parts of their product due to the bugs in them, even though these buggy functions are provided for my use. So it's not something hidden I'm trying to exploit here - it's part of their documented feature set.

Are they in their full rights to revoke my license when I violate this particular rule from the EULA?

Bonus question:

I am in the European Union, while the company is in the USA. Does that make a difference, i.e. are there laws in Europe that help me with arguing for my case? (Let's ignore the often-heard argument that shrink-wrapped licenses are not enforceable - instead I want to focus solely on the issue of defects in a product.)

Sure, even if the company is in the wrong, they could still then disable my license, but I'd like to understand if I am in the wrong here by expecting that they're liable to either fix bugs or let me fix them myself. If there's some good arguments in my favor, I may also want to make this case more public, or at least suggest that to the company if they remain uncooperative.

  • Have you considered using another product? Generally under the circumstances you described you would have very little recourse under U.S. Law. I do not know about European laws and would be interested in finding out. But depending on how the product was sold and the agreement, it is likely the laws of USA would apply. Unless the license agreement between you and the company making this software includes certain clauses mandating the company fixes bugs in a reasonable amount of time, your only recourse is switching products.
    – Viktor
    Nov 24, 2015 at 17:06
  • I'm guessing the license doesn't make an exception for fixing bugs, and you don't have a contract or anything that says they will fix bugs or let you fix them, right? I suppose you could try to argue that it's unconscionable that there exist bugs that they won't fix and they won't allow you to fix - I'm not a lawyer but that sounds like a long shot.
    – Patrick87
    Nov 24, 2015 at 18:51
  • Of course I could stop using their product, but then I have to suffer the damages of having built upon me relying on them for 15 years. It would cost me a huge amount of time and thus money to move to another product. Even if the company went out of business today, I could still continue using it (and fixing bugs in it), so the risk is still less by keeping to use it than by abandoning it. Nov 25, 2015 at 9:32
  • This is a rather cheap software product for which I've paid a few thousand dollars over the years. Such products never come with guarantees about fixing bugs. Their EULA is pretty one-sided, denying me to fix bugs but taking no responsibility. My question here is to clarify whether such a one-side contract is even legal. Apparently, it is, at least in the US. Nov 25, 2015 at 9:34
  • 1
    Not in Europe, anyway. Not any more since five days: curia.europa.eu/juris/document/…
    – mirabilos
    Oct 17, 2021 at 0:04

1 Answer 1


It is likely that the law applying will be both that of the USA and your country. If you went to court this would be one of the things you argued over.

For example, Australian Consumer Law applies to any goods or services sold to a customer in Australia irrespective of where the vendor is located. Your jurisdiction may have similar laws.

At first blush you must comply with the term of the contract preventing reverse engineering. They would be within their rights to terminate the licence if you don't.

However, they probably have an obligation under your equivalent to the ACL to supply a product that:

  • is merchantable
  • is fit for purpose
  • does what it says it will do

If it doesn't then you have a right to terminate and get your money back, sue for damages and your country's government may prosecute.

  • I've talked to someone in Germany who has some experience with similar issues and has a similar position: If I made the purchase via internet from the vendor's US side, then US law would apply, mostly. If I bought it from a German merchant, I may have a better chance relying on German law. However, as the program is generally fit, the particular bug might be found to be a "negligible defect" and I'd lose my case. Also, I could claim damages, but with the same trouble of arguing that this is a severe issue. Nov 25, 2015 at 9:22
  • 2
    The thing that is still bothering me about all this is that in general, bugs in software are considered less of an issue than it's with defects in hardware. I don't believe that a car manufacturer could take away my right to drive their car if I found a defect in it and fixed it myself (provided I stayed within local safety laws). But then again, cars are not licenced but sold. Where it gets interesting, though, is the question what's going to happen with all the bugs that are in software that's now getting more and more into cars... Nov 25, 2015 at 9:26
  • Also, I believe that there is a difference between a purchased and a licensed software. In Germany, to my understanding, licensing is more like renting, putting more responsibility on the seller's side as well, i.e. they remain liable for defects that appear later during the rent period. In my particular case (which is the general case for more end-user software products), it seems though, that what I have is not a true (rental) license but rather a one-time sales contract. Nov 25, 2015 at 9:39
  • @ThomasTempelmann the car analogy is not applicable - you own the car, you only buy the right to use the software. A better analogy is if you think of renting a car - the car hire company can absolutely profit you from modifying their car.
    – Dale M
    Feb 10, 2021 at 22:20
  • You probably meant "prohibit" in place of "profit". The rent analogy is even less applicable than mine, because the car is a unique item that has to be shared between customers, so me modifying it would affect the further re-use of that very car. Whereas, with software, it's a private copy, and me modifying it would not affect other customers of the company, same as if I'd modify my own car. Oct 18, 2021 at 1:08

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