 In the free-software community, there has been some controversy over whether a public domain dedication constitutes a valid open-source license.In 2004, lawyer Lawrence Rosen argued in the essay "Why the public domain isn't a license" that software could not truly be given into public domain, a position that faced opposition by Daniel J. Bernstein and others.In 2011, the Free Software Foundation added CC0 to its free software licenses and called it "the preferred method of releasing software in the public domain," while in general recommending the GNU General Public License.