I sometimes get confused about copyright. I've heard two things

  1. The abstract idea is never protected, so you can 'copy' the idea behind someone else's work and use it as your own.
  2. Just changing the names/wording of someone else's work doesn't make it your own.

I don't get how 1. and 2. are compatible. If you were to actually change the fundamental structure/inner workings, then it would be a different thing all together? For example a lot of the computer programming code online isn't licensed to actually be used and is only intended to be learned from. How do you 'learn' from another's source code without copying it, as if you were to change it then it would be a different algorithm and thus a different program?

Obviously most things in life we learn, yet we don't always go around citing where we learned it from.

  • Algorithms can be implemented in a vast number of ways using the same code language, without having to copy or closely match the code previously written. There are many different programmes that all implement the same algorithm, or even the same set of algorithms, without breaching copyright. Your question has fundamental flaws in premise, hence a downvote.
    – user4657
    Dec 2, 2017 at 7:29
  • @Nij but what's the difference from learning from someone else's source code and re-implementing it, versus copying it and making the changes to suit your need? The end results would be (roughly) the same. You can't say re-implementing it does more than just change the flow and variable names around, because any substantial changes would mean it wouldn't be the same algorithm. Dec 2, 2017 at 10:24
  • You seem to not understand what programmes and algorithms are, or importantly the distinction between them.
    – user4657
    Dec 2, 2017 at 10:40
  • @Nij I would define a program as an implementation of an algorithm, but after searching have found there is no universal definition. Anyway are you going to make a point or keep presupposing your conclusion is correct? Dec 2, 2017 at 11:59
  • One algorithm can be implemented by many different programmes. Changing the programme does not necessarily change the algorithm, nor does writing a different programme require that it implement a different algorithm. My point has been made in the first comment: they're not the same thing yet you ignore the distinction.
    – user4657
    Dec 3, 2017 at 1:35

2 Answers 2

  • If you make an exact (or nearly exact) reproduction of a copyrighted work, that is clearly a copy and you have infringed its copyright unless you have permission (or an exception such as fair use applies). It does not matter if the reproduction is done mechanically or via memory.

  • If you take a copyrighted work, and make small mechanical changes, leaving the structure intact (say you change all the occurrences of 'John' to 'Fred' in a novel, or you translate the novel faithfully into another language) you have created a derivative work, and this still infringes copyright unless you have permission.

  • If you take ideas from a copyrighted work, and use them to build a new work, that work does not infringe.

Exactly where the line gets drawn between a paraphrase and a new work is a judgement call. In general if there is a close part-by-part structural similarity between the old and new works, it is probably a paraphrase and thus a derived work.

If the ideas come from multiple different sources, that argues for a new work rather than a derived work. Relying on facts from several different sources, rather than taking everything from a single source, suggests research rather than copying.

When handling software source code, particularly short segments of code implementing a single algorithm, such as might be written for a text on programming, sometimes the ideas more or less dictate the expression. When an expression is obvious and there are few options on how to create it, it may not be protected by copyright. The literary term used for this principle is Scènes à faire ("required scenes"). This is closely related to the "Merger doctrine". When the expression has merged with the idea so that there is only a single way or only a few reasonable ways to express the idea, the expression is considered part of the idea and is not protected by copyright.

Facts are not protected by copyright, although the expression of a fact may be. Lists of facts in a natural or obvious order are not protected either. Lists selected and arranged in a creative order will be protected.

For example, a biography reading something like:

John Jones was born in 1948. He grew up in Anytown. He Graduated from Anytown HS in 1966. John attended BigU university. He graduated with a BS in computer sciennce in 1971. John Moved to New City. He worked as a systems programmer for DynaTech. He invented several new algorithms, including the much used Mastersort algorithm. In 1998 John won the Turing Award. John died in 2012.

This is a very basic biography, in strictly chronological order, listing facts with no creative expression. Copying this paragraph would not infringe copyright. It is not original enough for protection. But if it were expanded to several pages which told the story of John's life in expressive detail, including anecdotes of his time at BigU, what his co-workers at DynaTech thought of him, and how other famous developers regarded him and his work, that would almost surely be an original work that could not be copied without permission.


If you change someone else's work, then you create a derived work, which according to copyright law requires permission of the copyright owner. The point is that you start with someone else's work and change it.

If you create your work from scratch, and without referring to someone else's work, then it is not a derived work and not copyright infringement. Taking someone else's idea - not their work - and writing something based on it is fine.

When you see code online, you can copy it, paste it into your project, modify it to fit your needs, and you get a derived work, which is copyright infringement if you don't have permission of the copyright owner. If you see the code online, study it, figure out how it works, and then based on your new knowledge add new code to your project, that is your own work. No copyright infringement.

Do you notice the word "copy" in "copyright"? It's there because copying is the essential part. It's not the end result that counts, it's how you get there. Like getting from A to B by walking through my garden might be trespassing, while getting from A to B by walking around my home and garden would be no legal problem. As I said, it's how you get there.

  • 1
    I still don't get it. If you memorize someone else's code and then write it (verbatim) out yourself without referring back to it, wouldn't that still be infringement? Now, if you learned their code, and wrote yours slightly differently, what's the difference between that and having copied and pasted theirs and made modifications to suit your needs? Does copyright actually pertain more to the process of how the work was created rather than the end result? Dec 3, 2017 at 12:38
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    @drinkbeer22 If you memorize something (e.g. a poem, a computer program, etc.) and reproduce it, that is a copy. If you memorize a poem and then produce your own poem that is not a copy, then it is initially presumed not to be a copy. However, if I read your "non-copied poem" and it turns out that it is very similar to my poem, which I published first, I might suspect that your "non-copied poem" is actually based on mine, i.e. a derivative work. Whether this suspicion is valid or whether it would stand up in a court case is another question, however.
    – Brandin
    Dec 4, 2017 at 23:09

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