I'm reading "Open Source Licensing" by Lawrence Rosen.

At page 30 there is written:

A patent differs from a copyright in a fundamental way: A copyright prevents a third party from copying or modifying the original work, but a patent restricts everyone who uses the patented invention whether the invention has been copied or not. Even someone who independently creates the same invention and doesn’t copy the first inventor still cannot make, use, sell or offer for sale, or import the patented invention because he’s not the first inventor. It makes no difference whether the second inventor even knew of the first invention

So if I independently create a work of art, let's say a fiction book, can I make, use sell or offer for sale it?

Let's say I independently create "Harry Potter and the Philosopher Stone" by J. K. Rowling.

Of course I cannot do that without knowing at least what the book is about. I have to at the very least read the Wikipedia page, or a synopsis of the book. Or maybe the book itself. Otherwise I don't know what to write.

Of course I won't copy from the book, just read the synopsis and make my own.

But then that would be a derivative work right? And that is still prohibited by copyright law.

So the difference doesn't seem to spur from the law. The difference seems to be that is impossible to replicate a copyrighted work without "using" it in some way.

While it is possible instead to "reinvent" something.

Is my understanding right?

  • Keep in mind this only applies in the period of time the copyright or patent is valid. There are many literary works based on works where the copyright has expired, such as the Bible and Shakespeare.
    – user71659
    Oct 22, 2023 at 18:46
  • @user71659 "copyright has expired" does not describe the Bible or Shakespeare. These works never had copyright protection.
    – phoog
    Oct 22, 2023 at 20:06

4 Answers 4


If you had never heard about Harry Potter, and you wrote a book identical word by word with one of the Harry Potter novels, that would be completely legal and not copyright infringement. There are two problems: One, no court would believe you. Two, it’s about as likely as winning the lottery about 50,000 times in a row. Not going to happen.

However, if I had a great idea for a book, and told three people about my great idea, and each of them was a talented author who liked the idea, and turned it into a book, you would have three books based on the same idea. If I told them not just a simple idea, but an outline say why A hates B, how he prepares to kill them in an ingenious way, and how a clever detective solves the puzzle, you might have three very similar books. With no copyright infringement and legal.

Now with patents, the first difference is that the expression doesn’t count. What counts is what an invention does and how it does it. And if I had an idea for a new machine, being too lazy to turn it into a patent myself, and told my idea to 3 people, they could build non-identical machines that work in the same way, and only one could get a patent. The other two will fail to get a patent.

  • Only the inventor can obtain a patent. If it could be proved that gnasher729 had the original idea and told it to 3 people and one of them obtained a patent while claiming to be the inventor, the patent could be challenged and found invalid. Oct 22, 2023 at 18:45
  • 3
    The original idea is not yet an invention. Well, it depends. Usually you have an idea, and the hard part is getting it to work. But if I have just the idea, that's usually not enough.
    – gnasher729
    Oct 23, 2023 at 2:16
  • 1
    @GerardAshton to elaborate, to be patentable the invention has to be described in sufficient detail that someone could build it with no further creative input. Not quite a recipe but almost.
    – Dale M
    Oct 24, 2023 at 11:28
  • @Dale M Yes, you correctly described the amount of detail needed to obtain a patent. But if someone provided important creative non-public ideas and was not included on the application, at least as a co-inventor, I'm not sure that the patent would be valid. Oct 24, 2023 at 12:03

“Otherwise I don't know what to write”

is the point. Independently creating means independently creating. If you need to read it to independently create it you are not independently creating it.

In a clean room copyright-free creation exercise you do read a specification of the behavior of software but not the software itself. I can’t think of an analogy of a specification for Harry Potter.


If you wrote your own version of "Harry Potter and the Philosopher Stone" based on the book or its summary, it would not be a case of independent creation. I agree with your assumption that in this scenario, your work would probably be judged to be a derivative of the earlier copyrighted work, although the determination of what makes a work derivative is not precisely defined and would depend on the specific facts of what you wrote.

A derivative work is defined in the United States as follows:

A “derivative work” is a work based upon one or more preexisting works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which a work may be recast, transformed, or adapted. A work consisting of editorial revisions, annotations, elaborations, or other modifications which, as a whole, represent an original work of authorship, is a “derivative work”.

(17 U.S. Code § 101)

As you can see, this definition is broad and vague ("any other form in which a work may be recast, transformed, or adapted"). Whether a work is derivative of a prior work will often be a matter of interpretation that is not entirely clear until it is decided in court, although there are some categories of works for which the answer is definitely established by precedent (for example, translations from one language to another are unquestionably derivative works). An additional complication in the United States is the doctrine of fair use, which says that in certain circumstances (such as parody) a derivative work does not infringe the original copyright.

See also

The vagueness of what "derivative work" means in the context of copyright is the reason why in software, a "clean room" approach to implementing equivalent functionality is often followed, as mentioned in George White's answer.

The "clean room" approach does not provide a defense to patent infringement.


The crucial difference is how ideas are handled: they can be patented but not copyrighted.

In a nut shell, it can be said that patents protect ideas, and copyright protects expressions.

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