After 25 years of copyleft enforcement and compliance work, is copyleftsucceeding as a strategy to defend software freedom? This talk explores thehistory of enforcement of the GPL and other copyleft licenses, and considersthis question carefully. Attendees who have hitherto not followed the currentand past debates about copyleft licenses and their enforcement can attend thistalk and learn the background, and can expect to learn enough to providesalient and informed feedback of their own opinions about the processes behindupholding copyleft. The [first GPL enforcement action was done by Richard Stallman against NeXTComputers in 1989](https://www.gnu.org/philosophy/pragmatic.en.html),regarding Objective C support in GCC. For 25 years, GPL enforcement hasremained a regular but rarely mainstream activity in Open Source and FreeSoftware projects. Very few projects enforce their[copyleft](https://copyleft.org/) licenses; most live with regular violationsand merely ignore them, or simply beg violators to comply. Even under the now-published and publicly discussed [Community Principles ofGPL Enforcement](https://sfconservancy.org/copyleft-compliance/principles.html), co-drafted by Software Freedom Conservancy andthe Free Software Foundation, GPL enforcement is regularly criticized andquestioned. Those of us who enforce the GPL get wildly inconsistent feedbackfrom the community: some copyright holders recruit organizations likeConservancy and FSF to enforce as much as possible, others often complainingthat we simply don't enforce enough, and still others call for a completemoratorium on GPL enforcement. Meanwhile, not all enforcement abides by community principles. For-profitenforcers, who have existed for decades, use copyleft licenses in a manner notintended by the license drafters: to captiously convince "customers" that theymust buy proprietary licenses, or otherwise pay, to incorporate Open Sourceand Free Software into their products. This complex landscape has become almost impenetrable for the average FLOSSdevelopers who merely wish their code to remain forever free and libre. Thistalk will provide the basic history and background information about the stateof copyleft in our community, and set the stage for all developers to giveinformed feedback to organizations that stand up for copyleft.