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The Open Source Definition
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The Open Source Definition (OSD) is a policy document published by the Open Source Initiative in 1998[1]. Derived from the Debian Free Software Guidelines written by Bruce Perens, the definition is the most common standard for open-source software. The definition has ten criteria, such as requiring freely accessed source code and granting the open-source rights to everyone who receives a copy of the program. Covering both copyleft and permissive licenses, it is effectively identical to the definition of free software, but motivated by more pragmatic and business-friendly considerations. The Open Source Initiative's board votes on proposals of licenses to certify that they are compliant with the definition, and maintains a list of compliant licenses on its website. The definition has been adapted into the Open Knowledge Foundation's Open Definition for open knowledge and into open hardware definitions.
History
[edit]There have been several attempts to define open source and free software. Amongst the earliest was Free Software Foundation's Free Software Definition, which then defined as the three freedoms of Free Software (Freedom Zero was added later). Published versions of FSF's Free Software Definition existed as early as 1986, having been published in the first edition of the (now defunct) GNU's Bulletin.[2]
Debian Free Software Guidelines
[edit]The Debian Free Software Guidelines (DFSG) was first published together with the first version of the Debian Social Contract in July 1997.[3] The primary author was Bruce Perens, with input from the Debian developers during a month-long discussion on a private mailing list, as part of the larger Debian Social Contract. Perens was copied to an email discussion between Ean Schuessler (then of Debian) and Donnie Barnes of Red Hat, in which Schuessler accused Red Hat of never elucidating its social contract with the Linux community. Perens realized that Debian did not have any formal social contract either, and immediately started creating one. The (then) Three Freedoms, which preceded the drafting and promulgation of the DFSG, were unknown to its authors.[4]
The guidelines were:
- Free redistribution.
- Inclusion of source code.
- Allowing for modifications and derived works.
- Integrity of the author's source code (as a compromise).
- No discrimination against persons or groups.
- No discrimination against fields of endeavor, like commercial use.
- The license needs to apply to all to whom the program is redistributed.
- License must not be specific to a product.
- License must not restrict other software.
- Example licenses: The GNU GPL, BSD, and Artistic licenses are examples of licenses considered free.[3][5]
Open source
[edit]As Netscape released the open-source Mozilla browser in 1998, Bruce Perens again drafted a set of open-source guidelines to go with the release.[6] It has been claimed that the Open Source Definition was created by re-titling the exact text of the DFSG.
A modified version of this definition was adopted by the Open Source Initiative (OSI) as the Open Source Definition.[7][8] The OSI uses the label "open source", rather than "free software", because it felt that the latter term had undesirable ideological and political freight, and it wanted to focus on the pragmatic and business-friendly arguments for open-source software.[7] It adopted a closed rather than membership-driven organizational model in order to draft the definition and work together with a wider variety of stakeholders than other free or open-source projects.[7]
Once the DFSG became the Open Source Definition, Richard Stallman saw the need to differentiate free software from open source and promoted the Free Software Definition.[9]
Debian diverges
[edit]In November 1998, Ian Jackson and others proposed several changes in a draft versioned 1.4, but the changes were never made official. Jackson stated[10] that the problems were "loose wording" and the patch clause.
The Debian General Resolution 2004-003,[11] titled "Editorial amendments to the social contract", modified the Social Contract. The proposer Andrew Suffield stated:[12]
- "The rule is 'this resolution only changes the letter of the law, not the spirit'. Mostly it changes the wording of the social contract to better reflect what it is supposed to mean, and this is mostly in light of issues that were not considered when it was originally written."
However, the change of the sentence "We promise to keep the Debian GNU/Linux Distribution entirely free software" into "We promise that the Debian system and all its components will be free" resulted in the release manager, Anthony Towns, making a practical change:[13]
- "As [SC #1] is no longer limited to 'software', and as this decision was made by developers after and during discussion of how we should consider non-software content such as documentation and firmware, I don't believe I can justify the policy decisions to exempt documentation, firmware, or content any longer, as the Social Contract has been amended to cover all these areas."
This prompted another General Resolution, 2004–004,[14] in which the developers voted overwhelmingly against immediate action, and decided to postpone those changes until the next release (whose development started a year later, in June 2005).
Criteria
[edit]Providing access to the source code is not enough for software to be considered "open-source".[15] The Open Source Definition requires that ten criteria be met:[16][7]
- Free redistribution[16]
- Source code must be accessible and the license must permit redistribution in the form of source code (rather than object code).[16] In order to modify the software, access to source code is required.[17]
- Derivative works must be allowed and able to be redistributed under the same licensing terms as the open-source product[16]
- The license may require that the original software be distributed intact, but only if modifications are able to be distributed as patches without restriction.[16][17]
- No discrimination between users[16]
- No discrimination between uses, including commercial use[16]
- Everyone who receives a copy of the program is granted all the open-source rights[16]
- The license must cover all the code, not a particular product or distribution.[16][17]
- There may not be restrictions on other software distributed at the same time[16]
- Technological neutrality—cannot restrict use to any particular technology.[16] For example, a license that requires a user to click a box agreeing to it is not free because the work cannot be distributed as a paper copy.[17]
The Open Source Definition is available under a Creative Commons (CC BY 4.0) license.[18] It covers both copyleft—where redistribution and derivative works must be released under a free license—and permissive licenses—where derivative works can be released under any license. It is part of the open source movement rather than the free software movement, and seeks to promote the availability of open-source software for anyone seeking to reuse it, even the makers of proprietary software.[7][19][17] It does not address warranty disclaimers, although these are very common in open-source software.[17] The definition does not specify a governance structure for open-source projects.[7]
Compliant licenses
[edit]The criteria are used by the OSI to approve certain licenses as compatible with the definition, and maintain a list of compliant licenses. New licenses have to submit a formal proposal that is discussed by the OSI mailing list before it is approved or rejected by the OSI board. Seven approved licenses are particularly recommended by the OSI as "popular, widely used, or having strong communities":[20]
- Apache License 2.0
- BSD 3-Clause and BSD 2-Clause Licenses
- All versions of the GNU General Public License
- All versions of the GNU Lesser Public License
- MIT License
- Mozilla Public License 2.0
- Common Development and Distribution License (CDDL)
- Eclipse Public License version 2.0
Application
[edit]Software
[edit]Most discussions about the DFSG happen on the debian-legal mailing list. When a Debian Developer first uploads a package for inclusion in Debian, the ftpmaster team checks the software licenses and determines whether they are in accordance with the social contract. The team sometimes confers with the debian-legal list in difficult cases.
Non-"software" content
[edit]The DFSG is focused on software, but the word itself is unclear—some apply it to everything that can be expressed as a stream of bits, while a minority considers it to refer to just computer programs. Also, the existence of PostScript, executable scripts, sourced documents[clarification needed], etc., greatly muddies the second definition. Thus, to break the confusion, in June 2004 the Debian project decided to explicitly apply the same principles to software documentation, multimedia data and other content. The non-program content of Debian began to comply with the DFSG more strictly in Debian 4.0 (released in April 2007) and subsequent releases.
GFDL
[edit]Much documentation written by the GNU Project, the Linux Documentation Project and others licensed under the GNU Free Documentation License contain invariant sections, which do not comply with the DFSG. This assertion is the end result of a long discussion and the General Resolution 2006-001.[21]
Due to the GFDL invariant sections, content under this license must be separately contained in an additional "non-free" repository which is not officially considered part of Debian.
Multimedia files
[edit]It can be sometimes hard to define what constitutes the "source" for multimedia files, such as whether an uncompressed image file is the source of a compressed image and whether the 3D model before ray tracing is the source for its resulting image.
debian-legal tests for DFSG compliance
[edit]The debian-legal mailing list subscribers have created some tests to check whether a license violates the DFSG. The common tests (as described in the draft DFSG FAQ)[22] are the following:
- "The Desert Island test". Imagine a castaway on a desert island with a solar-powered computer. This would make it impossible to fulfill any requirement to make changes publicly available or to send patches to some particular place. This holds even if such requirements are only upon request, as the castaway might be able to receive messages but be unable to send them. To be free, software must be modifiable by this unfortunate castaway, who must also be able to legally share modifications with friends on the island.
- "The Dissident test". Consider a dissident in a totalitarian state who wishes to share a modified bit of software with fellow dissidents, but does not wish to reveal the identity of the modifier, or directly reveal the modifications themselves, or even possession of the program, to the government. Any requirement for sending source modifications to anyone other than the recipient of the modified binary—in fact, any forced distribution at all, beyond giving source to those who receive a copy of the binary—would put the dissident in danger. For Debian to consider software free it must not require any such excess distribution.
- "The Tentacles of Evil test". Imagine that the author is hired by a large evil corporation and, now in their thrall, attempts to do the worst to the users of the program: to make their lives miserable, to make them stop using the program, to expose them to legal liability, to make the program non-free, to discover their secrets, etc. The same can happen to a corporation bought out by a larger corporation bent on destroying free software in order to maintain its monopoly and extend its evil empire. To be free, the license cannot allow even the author to take away the required freedoms.
Reception
[edit]The Open Source Definition is the most widely used definition for open-source software,[23] and is often used as a standard for whether a project is open source.[18] It and the official definitions of free software by the Free Software Foundation (FSF) essentially cover the same software licenses.[7][24] Nevertheless, there is a values difference between the free software and open source movements: the former is more based on ethics and values, the latter on pragmatism.[7]
Derived definitions
[edit]The Open Knowledge Foundation's Open Definition is substantially derivative of the Open Source Definition.[25]
The Open Source Hardware Statement of Principles is adapted from the Open Source Definition.[26][23]
See also
[edit]References
[edit]- ^ "History of the Open Source Initiative". Open Source Initiative. Retrieved 2025-10-27.
- ^ Richard M. Stallman, What is the Free Software Foundation?, GNU's Bulletin, Volume 1, No.1, February 1986
- ^ a b Bruce Perens (1997-07-04). "Debian's "Social Contract" with the Free Software Community". debian-announce mailing list.
- ^ Bruce Perens: "when I had to write license guidelines for Debian, the Four Freedoms document was unknown."
- ^ "Debian Social Contract". Debian. 2004-04-26.
- ^ Overly, Michael R. (2003). The Open Source Handbook. Pike & Fischer. p. 5. ISBN 978-0-937275-12-2.
- ^ a b c d e f g h Gardler, Ross; Walli, Stephen R (2022). "Evolving Perspective on Community and Governance". Open Source Law, Policy and Practice. Oxford University PressOxford. p. 47–48, 52. doi:10.1093/oso/9780198862345.003.0002. ISBN 978-0-19-886234-5.
- ^ Katz, Andrew (2022). "Everything Open". Open Source Law, Policy and Practice. Oxford University Press. p. 521. ISBN 978-0-19-260687-7.
- ^ Richard Stallman. "Why "Open Source" misses the point of Free Software". GNU website.
- ^ Ian Jackson: Draft new DFSG, debian-devel mailing list
- ^ General Resolution: Editorial amendments to the social contract
- ^ Andrew Suffield: Re: Candidate social contract amendments (part 1: editorial) (3rd draft), debian-vote mailing list
- ^ Anthony Towns: Social Contract GR's effect on Sarge, debian-devel mailing list
- ^ General Resolution: Sarge Release Schedule in view of GR 2004-003
- ^ Greenleaf, Graham; Lindsay, David (2018). Public Rights: Copyright's Public Domains. Cambridge University Press. p. 485. ISBN 978-1-107-13406-5.
- ^ a b c d e f g h i j k Erlich, Zippy (2007). "Open Source Software". Handbook of Research on Open Source Software. IGI Global. pp. 187–188. ISBN 978-1591409991.
- ^ a b c d e f Laurent, Andrew M. St (2004). Understanding Open Source and Free Software Licensing: Guide to Navigating Licensing Issues in Existing & New Software. O'Reilly Media, Inc. pp. 9–11. ISBN 978-0-596-55395-1.
- ^ a b Mertic, John (2023). Open Source Projects - Beyond Code: A blueprint for scalable and sustainable open source projects. Packt Publishing Ltd. p. 5. ISBN 978-1-83763-385-2.
- ^ Meeker, Heather J. (2008). The Open Source Alternative: Understanding Risks and Leveraging Opportunities. John Wiley & Sons. pp. 21–22. ISBN 978-0-470-25581-0.
- ^ Smith, P McCoy (2022). "Copyright, Contract, and Licensing in Open Source". Open Source Law, Policy and Practice. Oxford University PressOxford. pp. 108–111. doi:10.1093/oso/9780198862345.003.0003. ISBN 978-0-19-886234-5.
- ^ General Resolution: Why the GNU Free Documentation License is not suitable for Debian main
- ^ The Debian Free Software FAQ
- ^ a b De Maria, Carmelo; Díaz Lantada, Andrés; Di Pietro, Licia; Ravizza, Alice; Ahluwalia, Arti (2022). "Open-Source Medical Devices: Concept, Trends, and Challenges Toward Equitable Healthcare Technology". Engineering Open-Source Medical Devices. Cham: Springer International Publishing. p. 4. doi:10.1007/978-3-030-79363-0_1. ISBN 978-3-030-79362-3.
- ^ Kelty, Christpher M. (2008). "The Cultural Significance of free Software – Two Bits" (PDF). Duke University Press. p. 99. Archived (PDF) from the original on 2016-03-04. Retrieved 2016-02-24.
- ^ Martin, Victoria (2022). The Complete Guide to Open Scholarship. Bloomsbury Publishing. p. 27. ISBN 979-8-216-06415-2.
- ^ Bonvoisin, Jérémy; Mies, Robert; Boujut, Jean-François; Stark, Rainer (2017). "What is the "Source" of Open Source Hardware?". Journal of Open Hardware. 1 (1) 5. doi:10.5334/joh.7. ISSN 2514-1708.
External links
[edit]- The Open Source Definition
- The Open Source Definition by Bruce Perens, Open Sources: Voices from the Open Source Revolution, January 1999, ISBN 1-56592-582-3
- Debian Social Contract and Free Software Guidelines
- debian-legal list, with archives from previous discussions
- Draft DFSG FAQ
- Section A.1.3 of Why OSS/FS? Look at the Numbers! identifies some of the major issues discussed by debian-legal.
- List of software licenses currently found in Debian
- The DFSG and Software Licenses Debian wiki
The Open Source Definition
View on GrokipediaHistory
Origins in Debian Free Software Guidelines
The Debian Free Software Guidelines (DFSG) originated as a set of criteria for determining what constitutes free software within the Debian project. Drafted primarily by Bruce Perens, the guidelines were refined through a month-long email discussion among Debian developers in June 1997 before being incorporated as Section 2 of the Debian Social Contract, version 1.0, ratified on July 5, 1997.[7] The DFSG outlined ten specific principles focused on ensuring users' practical abilities to run, study, share, and modify software, without embedding explicit moral or ideological requirements beyond these functional freedoms.[8] These ten points directly templated the Open Source Definition (OSD), which Perens adapted by rephrasing the DFSG to emphasize pragmatic licensing terms suitable for broader industry adoption, stripping away Debian-specific references while retaining the core structure of distribution and modification rights.[1] The adaptation occurred in early 1998, amid growing commercial interest in source code release, such as Netscape's January 29, 1998, announcement to open-source its browser, highlighting the need for a neutral, non-proprietary framework that prioritized verifiable permissions over prescriptive ethics.[9] Unlike the Free Software Foundation's emphasis on ethical imperatives, the DFSG's formulation favored empirical enforceability of rights, influencing the OSD's role as a certification standard for licenses enabling collaborative development without ideological barriers.[10] This foundation underscored a shift toward causal mechanisms of innovation through unrestricted access and derivative works, rather than appeals to user solidarity.Formation of the Open Source Initiative
The Open Source Initiative (OSI) was established in late February 1998 as a nonprofit organization dedicated to promoting open source software through the stewardship of a standardized definition and license certification process.[2] It was cofounded by Bruce Perens, then Debian project leader, and Eric S. Raymond, author of The Cathedral and the Bazaar, who served as OSI's initial president and vice president, respectively.[2] The formation responded to the growing interest in non-proprietary software development following Netscape's January 1998 announcement to open-source its browser code, but sought a pragmatic framework to encourage broader industry participation beyond the Free Software Foundation's (FSF) emphasis on user freedoms as moral imperatives.[11] The OSI's creation stemmed from a strategic effort to reframe "free software"—a term associated with Richard Stallman's FSF and its philosophical commitments—as "open source," highlighting practical benefits like collaborative development and interoperability to appeal to businesses wary of ideological connotations.[12] This rebranding aimed to facilitate adoption by corporations and governments without mandating the FSF's four essential freedoms as ethical absolutes, instead focusing on verifiable license criteria that enable commercial viability and innovation.[2] Perens initially adapted the Debian Free Software Guidelines into the Open Source Definition (OSD) as a neutral benchmark, though he later resigned from OSI in July 1998 over disagreements regarding the dilution of free software principles.[2] In March 1998, the OSI released version 1.0 of the OSD, establishing ten criteria for licenses to qualify as open source, including free redistribution, derived works allowance, and source code integrity preservation.[1] Early objectives centered on creating an authoritative list of compliant licenses to reduce legal ambiguity, certify software against the OSD, and build ecosystem trust through education and advocacy, thereby accelerating open source's integration into enterprise environments.[13] This certification role positioned OSI as a steward independent of any single project or ideology, contrasting with the FSF's copyleft-focused approach.[14]Key Versions and Revisions
The Open Source Definition (OSD) was first published by the Open Source Initiative (OSI) in February 1998, adapted from the Debian Free Software Guidelines by removing Debian-specific references while preserving core principles of software freedom.[2] This initial version established ten criteria for open source licenses, emphasizing free redistribution, source code availability, and derived works without restrictions on commercial use or modification.[1] Subsequent iterations through version 1.3 in 1999 introduced minor editorial refinements for clarity, such as explicit language on license compatibility and non-endorsement requirements, but avoided substantive alterations to maintain interpretive consistency.[1] By 2007, the OSD reached version 1.9 on March 22, incorporating limited clarifications to address evolving interpretations, including strengthened wording in criterion 5 on patent grants to ensure licenses explicitly allow derivative works without patent encumbrances, and refinements to criterion 6's anti-discrimination clauses to preclude field-of-endeavor restrictions while permitting narrow ethical safeguards against malicious use.[1] These changes were conservative, focusing on precision rather than expansion, as evidenced by OSI's annotated version retaining the 1998 structure amid growing adoption in enterprise contexts.[1] No further textual modifications have occurred since, underscoring the document's design for enduring applicability despite advancements in cloud computing, mobile ecosystems, and artificial intelligence.[1] In 2020, OSI and community forums debated potential revisions to incorporate contemporary concerns like sustainability mandates or AI-specific freedoms, with proposals suggesting additions for data transparency or environmental compliance.[15] [16] These were ultimately rejected, prioritizing textual stability to preserve legal predictability and avoid fragmenting the global open source ecosystem, where over 1,000 licenses had been evaluated against the unchanged criteria.[15] This conservatism reflects OSI's rationale that the OSD's principles—rooted in practical freedoms rather than prescriptive updates—remain robust, even as separate initiatives like the Open Source AI Definition emerged without altering the core text.[17]Core Criteria
The Ten Criteria in Detail
The Open Source Definition (OSD), version 1.9 as maintained by the Open Source Initiative (OSI), specifies ten criteria that a software license must meet to qualify as open source. These criteria form the authoritative standard for OSI approval, requiring licenses to enable unrestricted access, modification, and redistribution while prohibiting discriminatory or restrictive clauses that undermine openness. Compliance is determined by the literal terms of the license text, ensuring predictability and verifiability in classification.[1] 1. Free Redistribution. This criterion mandates that the license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources, nor require a royalty or other fee for such sale. It ensures that open source software can be freely incorporated into larger distributions without financial barriers, promoting widespread dissemination without vendor lock-in.[1] 2. Source Code. The program must include source code and allow distribution in both source and compiled forms. If source code is not distributed with a product, a well-publicized means of obtaining it must exist for no more than a reasonable reproduction cost—preferably free Internet download—and the source must be the preferred form for modification by a programmer. Deliberately obfuscated code or intermediate forms like preprocessor outputs are prohibited. This provision guarantees that users can inspect, debug, and improve the software, distinguishing open source from proprietary binaries.[1] 3. Derived Works. The license must permit modifications and derived works, allowing their distribution under the same terms as the original software's license. This enables collaborative evolution of software, fostering innovation through community contributions without requiring relicensing for changes.[1] 4. Integrity of The Author’s Source Code. Restrictions on distributing modified source code are permitted only if the license allows "patch files" for build-time modifications and explicitly permits distribution of software built from such modified sources. Derived works may be required to use different names or version numbers. This balances authorial control over the original codebase with the need for extensibility, preventing unauthorized substitutions while allowing verifiable alterations.[1] 5. No Discrimination Against Persons or Groups. The license must not discriminate against any person or group of persons. This prohibits clauses targeting individuals, organizations, or demographics, ensuring universal applicability and preventing exclusionary practices that could fragment the user base.[1] 6. No Discrimination Against Fields of Endeavor. The license must not restrict use in specific fields, such as business or genetic research. It safeguards against limitations that confine software to non-commercial or approved domains, upholding its utility across diverse applications without ideological preconditions.[1] 7. Distribution of License. Rights granted by the license must extend to all recipients upon redistribution, without requiring additional agreements. This automates propagation of freedoms, avoiding administrative hurdles that could dilute openness in downstream distributions.[1] 8. License Must Not Be Specific to a Product. Rights must not depend on inclusion in a particular software distribution; extraction and standalone use or redistribution must preserve the original freedoms for all parties. This prevents bundling dependencies that erode portability and independence.[1] 9. License Must Not Restrict Other Software. The license cannot impose conditions on accompanying software, such as mandating it be open source. It isolates the licensed program's terms, allowing flexible integration with proprietary or other elements without coercive spillover.[1] 10. License Must Be Technology-Neutral. No provision may depend on specific technologies or interface styles. This ensures enduring applicability amid evolving tools and platforms, avoiding obsolescence tied to particular implementations.[1]Design Principles and Rationale
The Open Source Definition's criteria derive from the principle that unrestricted access to source code maximizes software evolution by enabling diverse contributors to inspect, modify, and redistribute it without barriers to entry or use. This facilitates causal chains of innovation where code derivatives proliferate, fostering competition and rapid adaptation as empirical patterns in software development demonstrate that open access correlates with accelerated feature development and bug resolution compared to proprietary silos. For instance, requirements for free redistribution and derived works ensure no royalties or modification restrictions impede the flow of improvements, prioritizing long-term collaborative gains over short-term proprietary controls.[18][1] Central to the rationale is a deliberate rejection of mandatory reciprocity mechanisms, such as copyleft, which could deter commercial entities from building upon open code due to enforced openness of their extensions. By permitting permissive licenses that allow proprietary forks or integrations, the OSD accommodates real-world incentives for investment, recognizing that hybrid models—where open cores support closed enhancements—have empirically driven widespread adoption and sustainability in projects like operating systems and libraries. This avoids ideological mandates, focusing instead on deployability to broaden participation and market penetration.[18] Provisions like non-discrimination against fields of endeavor address pragmatic IP constraints, ensuring licenses do not impose use limitations akin to patent exclusions, thereby safeguarding usability in commercial, research, or applied contexts. Such criteria evolved to counter emerging threats from patent assertions in the late 1990s and early 2000s, when explicit grants in compatible licenses became standard to affirm non-restrictive rights without diluting core freedoms. This balances innovation-enabling openness against legal realities, prioritizing verifiable interoperability over absolutist purity.[18][1]License Compliance and Approval
OSI Approval Process
The Open Source Initiative (OSI) maintains a structured license approval process to evaluate proposed licenses against the Open Source Definition (OSD), ensuring they permit free use, modification, and distribution while aligning with community norms. Submissions begin with posting the license text to the license-review mailing list, where the proposer must affirm compliance with key OSD criteria—particularly those related to redistribution, derived works, and non-discrimination—and provide details such as a unique name, SPDX identifier, and, for new licenses, justification of any gaps not addressed by existing approved licenses.[19][20] Public discourse follows, requiring the submitter to engage with community feedback, clarify ambiguities, and demonstrate the license's broad reusability through examples of potential or existing adoption by multiple independent entities, thereby providing empirical evidence of practical compliance rather than theoretical assertions.[19][20] The OSI License Committee then reviews the discussion thread, seeking consensus on whether the license meets all OSD tenets within an initial 60-day period, which may be extended for complex cases or revisions. If consensus emerges, the committee recommends approval or rejection to the OSI Board of Directors, which conducts a final vote; decisions are announced publicly on the mailing list, with approved licenses added to the official OSI registry. This multi-stage, transparent mechanism, formalized through community input and board oversight, minimizes subjective bias by prioritizing documented evidence and collective scrutiny over individual judgments.[19] Since its inception in 1998, the OSI has approved more than 100 licenses via this process, reflecting a deliberate restraint against proliferation by favoring reusable standards over bespoke variants. Post-2020 updates have enhanced procedural clarity, including refined submission requirements and categorization guidelines, amid increased scrutiny of submissions related to emerging domains like AI models and datasets. These changes underscore a heightened emphasis on transparency, as the OSI has separately advanced an Open Source AI Definition to address ambiguities in applying OSD principles to non-software artifacts, though traditional license approvals remain focused on software conformance.[4][21][22]Examples of Compliant and Non-Compliant Licenses
The MIT License, a permissive license approved by the Open Source Initiative (OSI) in 1999, complies with the Open Source Definition (OSD) by allowing unrestricted redistribution, modification, and commercial use, subject only to retaining the original copyright notice and disclaimer.[23] Similarly, the Apache License 2.0, OSI-approved since 2004, meets OSD criteria through provisions for source code distribution, derived works, and explicit patent licenses, while prohibiting patent retaliation against contributors; it powers major projects like the Android operating system.[24] The GNU General Public License (GPL) versions 2.0 and 3.0, classified as strong copyleft licenses and OSI-approved (GPLv2 in 1999, GPLv3 in 2007), conform to the OSD despite requiring derivatives to adopt the same license terms, as they ensure source availability and avoid discrimination against persons or fields of endeavor.[25] In contrast, licenses with non-commercial restrictions, such as those incorporating Creative Commons Non-Commercial (NC) clauses (e.g., CC BY-NC), fail OSD criterion 5 by discriminating against commercial fields of use, rendering them unsuitable for open source designation despite OSI approval of unmodified CC0.[1] The Server Side Public License (SSPL), introduced by MongoDB in 2018, was rejected by the OSI in 2019 for violating multiple OSD criteria, including requirements for additional service-level obligations on distributors (e.g., cloud providers) that hinder free redistribution and impose field-specific burdens beyond software modification.[19] Even OSD-compliant licenses like the GPL face practical enforcement challenges, as evidenced by Software Freedom Conservancy's litigation over BusyBox—a GPL-licensed utility. In December 2009, suits were filed against Best Buy, Samsung, Westinghouse, and others for distributing BusyBox in devices without providing required source code, leading to settlements, financial penalties, and a 2010 U.S. court injunction mandating cessation of violations; these cases underscore gaps in automatic compliance, relying on copyright holders for proactive legal remedies rather than inherent mechanisms.[26][27]Debian-Legal and Related Compliance Tests
The debian-legal mailing list, active since the late 1990s, enables Debian contributors to debate software legality, with a focus on vetting licenses against the Debian Free Software Guidelines (DFSG) for main archive inclusion.[28] These discussions apply DFSG-derived tests informally but rigorously to packaging decisions, serving as an ongoing practical benchmark for licenses' alignment with the Open Source Definition (OSD), which adapts the 1997 DFSG.[8] Debian-legal emphasizes tests ensuring licenses avoid post-distribution restrictions, such as the Tentacles of Evil test prohibiting authors from clawing back freedoms, and the Desert Island test verifying operability without external contact.[29]- Field-of-use neutrality: Licenses imposing domain-specific limits, like barring commercial use, violate DFSG principle 6 and are rejected from main, directing them to non-free; this mirrors OSD criterion 6 by demanding unrestricted application across endeavors.[29][30]
- Patent grants: Absent systematic patent audits due to feasibility issues, licenses failing to preclude rights revocation via patent claims or lacking implicit/explicit grants render software non-free, aligning with Debian's anti-patent stance.[29][31]
- Endorsement clauses: Overly broad prohibitions on implying endorsement or mandates for user actions (e.g., notifications) fail freedom tests, as seen in rejections like the Open Publication License, preventing encumbrances on derivative works.[29][30]
