A typical "EULA" attempts to reduce your rights, without any further consideration from you (you'll have already paid for it, etc). If you disagree, the authors like to claim that you are bound by their more restrictive terms anyway. That is what is legally dubious.
A copyleft license does the opposite: the software comes with an offer to grant you additional permissions should you choose to accept its terms. You have the option to decline, and nobody is claiming that your rights are in any way further restricted if you choose to decline.
Put another way, you are free to use GPL software without accepting the terms of the license. But if you don't accept the terms, then you violate copyright law every time you make copies of it.
Status quo: You can use the software. You're not allowed to redistribute copies or modified versions of the software.
EULA: You may only use the software if you agree to additional terms. Usage rights are restricted.
GPL: You may redistribute copies as well as modified versions as long as distribution happens under the terms of the GPL. Distribution rights are granted.
For example you can't make a contract in which I just pay you $50 per year. But you can have a contract in which I pay you $50 per year and in exchange you deliver me a girl scout cookie on the 7th of November every year.
The court doesn't (usually) care whether the deal made is a good idea, $50 for a girl scout cookie seems like terrible value, but it _is_ an exchange of two things of value.
Because the GPL spells out what you're getting and what you're swapping for it, it will always satisfy this idea of consideration. In contrast very often "click through" or "shrinkwrap" licenses don't really do so.
Additionally, GPL only grants you "additional freedoms" if you're willing to reciprocate. If you want to use it in a closed source work, it very much limits your freedoms. The phrase "permissive license" exist for a reason, and it explicitly excludes the GPL.
It's the copyright law which prevents you from using GPL software in closed source works, not the GPL. GPL doesn't care about proprietary software at all, leaving it at the mercy of status quo. It only grants some additional rights to users and developers of free software.
It is... disappointing that modern courts have allowed the First Sale doctrine to be watered down so that today there's every chance you will buy something, paying good money, and then be confronted with new "terms" for how you may use the thing you purchased. But it's not in general clear that such an approach is legal.
On what grounds do you have no right to use a copy of software you bought without obtaining an additional license from the vendor?
As for copying it's copyright, obviously, but I never understood what's the matter with merely using. IANAL but AFAIK in some EU countries it is recognized that there is no legal basis for EULAs and they officially are void, unless signed as a contract prior to the purchase, of course.
Not quite. There is no need to sign anything, what matters is if the EULA was included in the sale contract (so, the buyer was aware that the willingness of the seller to sell you the product depended on the buyer accepting those additional terms as part of the contract). On the other hand, if you do indeed sign an additional contract afterwards on your free will that limits your rights, that might very well be enforcable. But the point is that there is no legal necessity to sign such a contract in order to use the software that you have bought.
To use software you probably have to install it on your computer - this makes a copy of the software. Then when you run it you make another copy into your computer's memory, and additional copies in the the CPU's cache.
I don't agree with the above argument (I think fair use covers it), but I have heard it. It isn't hard to read the letter of the law and conclude the above is the correct interpretation. (you might need to see some money...)
I honestly do not know how to fix the letter of the law. There are too many special cases. If I have two computers can I install it on both? Can I install it for my family to use? When my computer fails can I install it on the replacement? The above are trick questions: I deliberately asked them to invite answers that imply I can install one copy of software on as many servers as I want for as many users as I want - this seems wrong.
"This book is sold subject to the condition that it shall not, by way of trade, be lent, resold, hired out, or otherwise disposed of without the publisher's consent in any form of binding or cover other than that in which it is published."
from https://books.google.com/books?id=v-yrLmQNRvsC&pg=PR4 , but there are many other examples.
Many publishers really didn't like used bookstores and libraries making a single book available to many people over time, replacing the covers as necessary due to wear instead of buying new copies of the book.
If it does not include an EULA, are you not allowed to use it? Does the same hold for computer games with an EULA?
Or does the existence of an an EULA hold your rights hostage until you agree to it?
No. A user is not required to agree with GNU GPL license terms to merely install and use some software licensed under GNU GPL. GPL comes into scene only when some (re)distribution of the code/binary happens.
So, GNU GPL has not much to do with End User License Agreement because the end user never have to agree with GNU GPL unless he/she is going to add one or more link to the chain of users.
Also, does the seller have to reimburse you if you decline the license (and of course return the copy)?
So you pay for the copy but not for the license, and you got the license free if you paid for the copy, right? (But of course that license comes with a lot of restrictions, just like the GPL.)
But the important thing seems to be that the GPL binds distributors. It's a contract between developers and distributors. (Sure, it's a contract between anybody that acquires a copy.)
Is there a coherent legal overview of this?
As to your last question: yes there is, people have written dozens of book about it. Your local university probably has a bunch of them in their library. If you're asking about a website where you can read in a few paragraphs the complete legal context with definitive answers to questions about general cases (i.e., no 'it depends' allowed) - then no, such a thing does not exist. Look at it this way: if a novice programmer goes onto LKML and says 'hey guys, I want to write an OS, can someone point me to an overview' - then at best he'd be pointed to some high-level overview Wikipedia pages, but most likely, people would snicker and press 'delete' (well actually he'd probably receive a bunch of abuse on how he should get off the list, but that's specific to the example I chose...)
FWIW, I did read a bunch of book like the ones I mentioned above when I was writing a paper on a EULA-related topic during my law degree, and as a result I don't make any blanket statements about the topic any more.
