I am working, with a co-author, on a data modeling toolbox that will someday be sold. Part of the functionality is the extremely common PCA, which we are doing in a more robust way. Thus, we need a PCA function that has the usual algorithm with some modifications. For non-commercial peer-review academic research, I could easily find PCA code that is already written, modify it to suit my needs and use it, citing the author in my research.
My co-author insists that in this commercial venture, it is entirely appropriate to do the same thing. We can take another author’s copyrighted code (ex “Copyright (c) 1997 by blah blah blah”, not necessarily a GNU license), modify it to suit our needs, and distribute it with the toolbox we are selling. He says that as long as we cite the original author, it’s entirely acceptable.
I’m just as strenuously insisting this is not legal, but have been unable to find straightforward documentation. Can someone point me to unambiguous documentation of this?
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Contact the author of the code you intend to modify and ask for permission in writing to do what your partner wants. That won’t cover you, but a strongly worded “don’t modify my code” letter might convince your partner that this is a bad idea.
As the many comments have pointed out, asking for legal advice from a bunch of strangers who don’t claim to be lawyers (let alone live in your country) is a bad idea.
If you’re going to make anything more than beer money it will be very important to be able to prove that you have clear rights (either ownership or appropriate FOSS license) to everything.
Talk to a local lawyer
Spending money on a lawyer is cheaper than defending (or worse, losing) a lawsuit.
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You don’t need to contact a lawyer for every question about law! Some issues are very straightforward.
You don’t say where you live, which makes it hard to give an appropriate reference. Here’s one for where I live: a UK government website on intellectual property law. Summary quote
You may need to get permission from a copyright owner if you wish to copy written work [including software] in any way, unless any exceptions apply [they don’t in your case]
Search for a website from your own government for a reference for your own country.
Going beyond the question. You might want to ask a lawyer to write an agreement for the original author to sign, to be sure it will stand up in court, or just choose an unrestrictive open source license like MIT.
It’s not the modification that’s the problem — modifications are of course your own work, and you own that part. The problem is the unmodified code, and the fact that you’re basing your work on someone else’s in the first place.
If your partner thinks it’s okay to use someone else’s work without permission, he doesn’t understand what copyright means.
May you reprint a copyrighted book and sell it*, even with proper attribution? No.
May you re-record a copyrighted song and sell it*, even with proper attribution? No.
May you re-use copyrighted code and sell it*, even with proper attribution? No.
One has to wonder how your partner would feel about someone taking your code and selling it without permission.
*without permission of the author
I think that it entirely depends on what you define as modifying. If you change his code but leave most of the work intact, you’re basing your copyrighted code on his copyrighted code.
If however you take his code and use it as inspiration for your code then your code is not based on his copyrighted code but on his (patented) implementation.
Basically: write your own implementation of what the original author did. Shouldn’t be hard because you can use his code as inspiration.
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