The effect of the optional restrictions of the GPLv3

I just thought a bit about the restrictions the GPLv3 allows, and I think I just understood their purpose and effect for the first time (correct me, if I'm wrong :) ).

What are the restrictions?

The GPLv3 allows developers (=copyright holders) to add selected restrictions, like forbidding the use of a certain brand name or similar.

The catch with them is, that any subsequent developer who adds anything is free to simply strip off the restrictions.

What is their effect?

Now I wondered for a long time, what that really gains us. today I then realized that subsequent develoeprs are only free to strip off the restrictions, as long as that doesn't violate any license of some part of the program.

That means, the GPLv3 restrictions simply have the effect of adding compatibility to other licenses, while keeping the option to strip off any restriction, when you replace the part under the other license with a more liberal licensed part.

So this doesn't place any additional burden on packagers, because they already have to check those other licenses for their restrictions. Now the GPLv3 description of the whole package clearly states what additional restrictions are inferred by the parts which are under different but compatible licenses.

While those parts where under seperate licenses before (and had to be checked), they can now be impcoved with GPLv3 code with additional restrictions.

And as soon as the GPLv3 code can stand on its own feet, the more restrictive licensed part can be replaces with GPLv3 code, and the restrictions can be removed again, making the work of the packagers easier.

Better still, the GPLv3 shows clearly the sum of all restrictions of the individual (differently but compatible licensed) parts, so packagers only need to check the GPLv3 license information to see all restrictions in a standardized format (GPLv3 additional restrictions).


Let's assume I find this great piece of software which says "do what you want but don't touch my brand", and I want to build my GPLv3 program on it. Let's call the piece of software "foo". So I just begin coding and use the GPLv3 for my parts (simply copyright message in my code files). For the whole package I add a license information ("license.txt" or "COPYING" or similar) which give the information

  "This program is licensed under the GPLv3 
  with the additional restriction that the brand 
  'foo' may not be used for derived products. 
  The additional restriction is inferred by the package foo.

  (plus license mumbo jumbo you can find at and copy 

Now someone else takes my program and improves it. But he also uses the package "blah" which also says that it's brand must not be violated. Now the combined license would be:

  "This program is licensed under the GPLv3 
  with the additional restriction that the brand 
  'foo' and the brand 'blah' may not be used for 
  derived products. 
  The additional restriction for brand 'foo' is inferred by the package foo.
  The additional restriction for brand 'blah' is inferred by the package blah. 

  (plus license mumbo jumbo you can find at and copy 

So now a group of free software activists takes offense at the restrictions. They don't want anyone to be restricted by copyright from using a brand. One reason could be that the brand protection was voided by some trademark action.

Now they can't just say "that brand isn't protected anymore", since the protection was reinforced by copyright law.

But they can just replace the parts under the more restrictive licenses with honest GPLv3 licensed parts - either by writing them or by finding a drop-in replacement. Now let's suppose they write the packages "bar" and "baz" which implement the functionality of "foo" and "blah". They now no longer use any parts under licenses which require additional restrictions, so they are free to remove them. As they release their package, the license information might read as follows:

  "This program is licensed under the GPLv3.  

  (plus license mumbo jumbo you can find at and copy 

If they are nice (and we assume they are) their changelog will also contain a line saying something like "replaced 'foo' and 'blah' which allowed us to remove the additional license restrictions to avoid using the brands 'foo' or 'blah'."

Final remark

As you see (and if I understand it correctly), the additional restrictions can be a great tool for freeing software from restrictions, because they allow you to combine GPlv3 code with somewhat restrictive licensed code and get rid off the restrictions later by replacing the more restrictive licensed parts.

And since the only allowed additional restrictions are those which don't harm the four freedoms of free software, you can still make sure that you use ethically sound software by simply checking whether it is GPL licensed.

So kudos to the designers of the GPLv3. They did such a great job that it took me two years to realize one of the many powerful tools they gave us with the GPLv3 - and I did take part in the public discussion of the GPLv3 since draft 1 (but I never watched a GPLv3 speech...).

Also, since the GPLv3 allows combination with the AGPLv3 software (which adds the restriction, that the source code must also be supplied when the software is used over a network), it gives us a clear path into the future where people might use more and more software "as a service", so it doesn't get executed on their local machine and the normal GPL alone isn't enough to protect our freedom.

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