As the GNU LibreDWG library is released under GPLv3 it can't be used by GPLv2 licensed LibreCAD (and FreeCAD) as their licenses are incompatible. A request also went to the FSF to relicense GNU LibreDWG as GPLv2, which was rejected. This controversy has been resolved by writing a new GPLv2 licensed library called libdxfrw, with more complete DWG support.
^Prokoudine, Alexandre (26 January 2012). "What's up with DWG adoption in free software?". libregraphicsworld.org. Archived from the original on 9 November 2016. Retrieved 3 November 2013. [Assimp's Alexander Gessler:] "Personally, I'm extremely unhappy with their [LibreDWG's — LGW] GPL licensing. It prohibits its use in Assimp and for many other applications as well. I don't like dogmatic ideologies, and freeing software by force (as GPL/GNU does) is something I dislike in particular. It's fine for applications, because it doesn't hurt at this point, but, in my opinion, not for libraries that are designed to be used as freely as possible." [Blender's Toni Roosendaal:] "Blender is also still "GPLv2 or later". For the time being we stick to that, moving to GPL 3 has no evident benefits I know of. My advice for LibreDWG: if you make a library, choosing a widely compatible license (MIT, BSD, or LGPL) is a very positive choice."
^Larabel, Michael (2013-01-24). "FSF Wastes Away Another "High Priority" Project". Phoronix. Archived from the original on 2016-11-09. Retrieved 2013-08-22. Both LibreCAD and FreeCAD both want to use LibreDWG and have patches available for supporting the DWG file format library, but can't integrate them. The programs have dependencies on the popular GPLv2 license while the Free Software Foundation will only let LibreDWG be licensed for GPLv3 use, not GPLv2.
^Prokoudine, Alexandre (2012-12-27). "LibreDWG drama: the end or the new beginning?". libregraphicsworld.org. Archived from the original on 2016-11-09. Retrieved 2013-08-23. [...]the unfortunate situation with support for DWG files in free CAD software via LibreDWG. We feel, by now it ought to be closed. We have the final answer from FSF. [...] "We are not going to change the license."