It has been a topic of discussion for a while now, however Rockstar recently made modding Grand Theft Auto V a violation of their terms of service, enforcing a ban on players found to be using mods. 

This wouldn't be a surprise for mods affecting the online mode, but it seems that even single player mods can get you banned. To justify the banning of players, some Rockstar representatives are referring players to the EULA where the following can now be found:

You agree not to:
[..] reverse engineer, decompile, disassemble, display, perform, prepare derivative works based on, or otherwise modify the Software, in whole or in part;

According to the new terms of service, unless there is a change in Rockstar’s EULA, the Grand theft Auto V modding scene, one of the biggest sell-points for the PC version, is not allowed to take off, effectively forcing players to choose between modding their game or the ability to play online. 

The Internet has taken to Steam, where Grand Theft Auto V’s review count has hit 6,529 negative reviews with no sign of slowing down. 

User G0LKS left the following review:

Good game but can’t recommend due to Rockstar’s shady practices…Banning people, who paid 60 freakin dollars, because they use mods to enhance their SP experience is abhorrent and violates the basic principles of PC gaming. It’s made even more ridiculous by the fact that most of these mods are harmless graphical fixes (such as the FOV mod) which serve to improve the already awesome game that rockstar has developed.

I hope the developers change their stance about this and do it soon.

Some users indicate that changing your Rockstar account username will “unbind” the activation code from the account since they are bound to the username and non-transferable, resulting in users getting the message “Rockstar activation code already in use.” when trying to launch the game.

Given Steam’s mod controversy, and Gabe Newell’s statement about the costs of angering the Internet (“yes, I mean pissing off the Internet costs you a million bucks in just a couple of days“), we can only hope Rockstar see its potential mistake, and fixes it before it is too late.

Rockstar Changes EULA - Can Ban Players For Modding GTA V