Editing Open-source license (section)

== Enforcement ==
{{main|Open source license litigation}}
[[File:Harald Welte 27C3.jpg|alt=Portrait of Harald Welte|thumb|upright|Early legal victories by programmer [[Harald Welte]] established a precedent for open-source software litigation in Germany.{{sfn|Ballhausen|2022|loc=sec.&nbsp;5.3}}]]

Free and open-source software licenses have been successfully [[Open source license litigation|enforced in civil]] court since the mid-2000s.{{sfn|Smith|2022|loc=sec.&nbsp;3.4.1}} In a pair of early lawsuits&mdash;[[Jacobsen v. Katzer]] in the United States and [[Open source license litigation#Welte v. Sitecom Germany (2004)|Welte v. Sitecom]] in Germany&mdash;defendants argued that open-source licenses were invalid.<ref>{{cite court |litigants=Jacobsen v. Katzer |vol=535 |reporter=F.3d |opinion=1373 |pinpoint= |court=[[Fed. Cir.]] |date=2008 |url=https://scholar.google.com/scholar_case?case=17776182574171214893 |access-date=2019-02-18 |quote=}}</ref><ref>{{cite court |litigants=Welte v. Sitecom |court=District Court of Munich |date=2004 |url=https://www.ifross.org/Fremdartikel/judgment_dc_munich_gpl.pdf |text=No. 21 O 6123/04}}</ref> Sitecom and Katzer separately argued that the licenses were unenforceable. Both the [[United States District Court for the Northern District of California|US]] and German courts rejected these claims. They ruled that the defendants could not have legally distributed the software if the licenses were unenforceable.{{sfn|Smith|2022|loc=sec.&nbsp;3.4.1}}{{sfn|Ballhausen|2022|loc=sec.&nbsp;5.3}}

Courts have found that distributing software indicates acceptance of the license's terms.{{sfn|Smith|2022|p=106}} Physical software releases can obtain the consumer's assent with notices placed on [[shrinkwrap]]. [[Online distribution]] can use [[clickwrap]], a digital equivalent where the user must click to accept.{{sfn|Rosen|2005|p=137}} Open-source software has an additional acceptance mechanism. Without permission from the copyright holder, the law prohibits redistribution.{{sfn|Rosen|2005|p=138}} Therefore, courts treat redistribution as acceptance of the license terms. These can include attribution provisions or source code provisions for copyleft licenses.{{sfn|Rosen|2005|loc=ch.&nbsp;6}}{{sfn|Meeker|2020|loc=17:04}}

Developers typically achieve compliance without lawsuits. Social pressures, like the potential for community backlash, are often sufficient.{{sfn|St. Laurent|2004|pp=158-159}} [[Cease and desist]] letters are a common method to bring companies back into compliance, especially in Germany.{{sfn|Ballhausen|2022|p=127}} A standard process has developed in the German legal system. FOSS developers present companies with a cease and desist letter. These letters outline how to come back into compliance from a violation. German judges can issue a court-mandated cease and desist order to unresponsive companies. Civil cases proceed if these first steps fail. The German procedural laws are clear and favorable to claimants.{{sfn|Ballhausen|2022|loc=sec.&nbsp;5.4}} 

Uncertainties remain in how different courts will handle certain aspects of licensing.{{sfn|Walden|2022|loc=sec.&nbsp;1.1}} For software in general, there are debates about what can be patented and what can be copyrighted. Regarding an application programming interface (API), the [[European Court of Justice]] noted in the 2012 ''[[SAS Institute Inc v World Programming Ltd|SAS Institute]]'' case that "ideas and principles which underlie [computer program] interfaces are not protected by copyright".{{sfn|Smith|2022|loc=sec.&nbsp;3.1.3}} In a [[Google LLC v. Oracle America, Inc.|similar 2021 case]], the US Supreme Court permitted the recreation of an API in a [[transformative use|transformative]] product under [[fair use]].<ref>{{cite court |litigants=Google LLC v. Oracle America, Inc. |vol=593 |reporter=U.S. |opinion= |pinpoint=1203 |court= |date=2021 |url=https://scholar.google.com/scholar_case?case=4050620474768552042#p1203}}</ref>

A long-debated subject within the FOSS community is whether open-source licenses are "bare licenses" or [[contract]]s.{{sfn|Walden|2022|loc=sec.&nbsp;1.1}} A bare license is a set of conditions under which actions otherwise restricted by IP laws are permitted.{{sfn|Smith|2022|loc=sec.&nbsp;3.4.1}} Under the bare license interpretation, advocated by the FSF, a case is brought to court by the copyright holder as [[copyright infringement]].{{sfn|Smith|2022|loc=sec.&nbsp;3.4.1}} Under the contract interpretation, a case can be brought to court by an involved party as a [[breach of contract]].{{sfn|Smith|2022|loc=sec.&nbsp;3.4.2}} US and French courts have tried cases under both interpretations.{{sfn|Smith|2022|loc=sec.&nbsp;3.4}} Non-profit organizations like FSF and the [[Software Freedom Conservancy]] offer to hold the rights to developers' projects to enforce compliance.{{sfn|Ballhausen|2022|loc=sec.&nbsp;5.4}}