One of the goals of the GNU General Public License version 3 was be more compatible with other open-source licenses. There is some concern, however, that this goal has not been achieved in relation to the Apache License 2.
As Allison Randal, president of The Perl Foundation, pointed out in a recent article on OReilly Radar, the rationale document for the latest GPLv3 draft (PDF link), states "We regret that we will not achieve compatibility of the Apache License, Version 2.0, with GPLv3, despite what we had previously promised."
In a January 2006 eWEEK interview, Richard M. Stallman, president of the FSF (Free Software Foundation) and chief author of the GPL, said: "The Apache license is incompatible with GPL Version 2 because of a trademark clause and a patent retaliation clause, as I recall. I believe we have made both of those things compatible now."
That, however, is no longer the case and Randal said the FSF is wrong to believe that the Apache License 2 is incompatible with the GPLv3. In the GPLv3 rationale draft, the authors explained, "Under section 9 of the Apache license, downstream redistributors must agree to indemnify upstream licensors under certain conditions."
The offending section of the Apache License 2 reads:
"While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability."