Short answer: copyright law does not stop your customers from reverse engineering your software, your contract has to, and even then courts have carved out fair-use exceptions for interoperability. So the reverse engineering clause in your EULA or SaaS terms is doing real work, and you want it drafted correctly.
This is a hot issue. Whether you ship on-premises software or run a SaaS platform, it is worth understanding how reverse engineering law actually works, because your partners, competitors, and customers may already know, and some of them may be legally reverse engineering your product right now. Most software and SaaS contracts specifically prohibit reverse engineering, and that prohibition has to be in the contract because copyright does not provide it by default.
Why Your Contract Has to Say It.
Copyright stops people from copying your code, but it does not, by itself, stop someone from studying how your software works. That is why the no-reverse-engineering clause exists. The good news for vendors is that courts enforce it. In Bowers v. Baystate Technologies, a federal appeals court held that a contractual ban on reverse engineering is enforceable and is not preempted by copyright, even where copyright’s fair use doctrine might otherwise have allowed it. Your contract clause can reach further than copyright does, which is exactly why getting it right matters.
The Fair Use Exceptions.
On the copyright side, there are situations where reverse engineering is allowed, usually under fair use. In Sega v. Accolade and Sony v. Connectix, courts treated intermediate copying done to achieve interoperability as fair use. So absent a contract, a competitor may have real room to reverse engineer for interoperability (see the EFF’s reverse-engineering FAQ). The contract is what closes that gap.
The DMCA Layer.
Then there is the Digital Millennium Copyright Act (17 U.S.C. section 1201), which makes it illegal to circumvent technological measures that control access to a work. Every three years the Library of Congress grants exemptions, and over the past decade they have chipped away at the blanket prohibition, allowing circumvention in narrow cases like letting a phone owner install independent apps or switch carriers. The DMCA anti-circumvention rules sit on top of, and separate from, both copyright and your contract.
The European Angle.
If you sell into the EU, note that European law has long allowed reverse engineering for interoperability under the Software Directive, within limits. That is one more reason a flat contractual ban behaves differently across jurisdictions, and a reason to flag any EU-facing deal early rather than assume your US clause travels.
The Drafting Takeaway.
The interaction between your contract, copyright, the DMCA, and foreign law gets complex fast. The practical move is to make sure the reverse engineering prohibition in your agreement is clear, broad where it can be, and consistent with the rest of your license grant. Getting that prohibition right is part of drafting a software license properly, and it lives alongside the other restrictions you put in a license. The exact language differs depending on whether you are on an EULA or a SaaS subscription model (see SaaS Agreement vs. Software EULA: Which Template Do You Need?).
Frequently Asked Questions.
Does copyright stop reverse engineering? Not reliably. Copyright stops copying, but studying how software works can fall under fair use, especially for interoperability. The reliable prohibition comes from your contract.
Is a no-reverse-engineering clause enforceable? Yes. In Bowers v. Baystate, a court enforced a contractual ban and held it was not preempted by copyright, so the clause can reach further than copyright alone.
Does the same clause work for EU customers? Not necessarily. The EU Software Directive permits reverse engineering for interoperability within limits, so flag EU-facing deals and adjust the clause rather than assuming your US language travels.
Trust me on this one: get the clause right.
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Disclaimer:
This post is for informational and educational purposes only, and is not legal advice. You should hire an attorney if you need legal advice, which should be provided only after review of all relevant facts and applicable law.
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