Viewpoint... The practical point of view of the copyright infringement lawsuit based on the GPL protocol secondary development software.

The GPL (General Public License) is an open source protocol created by Richard Stallman, the spiritual leader of the free software movement and the founder of the GNU Project and the Free Software Foundation. There are three versions of the GPL protocol so far, including GPLv1 released in 1989, GPLv2 released in 1991 and GPLv3 released in 2007. Linux, as the most widely known open source system, uses the GPL protocol.

The main content of the GPL protocol is: as long as a product of the GPL protocol is used in a software (using reference to class library reference, modified code or derivative code), the software product must also adopt the GPL protocol and must also be open source and free. This is called "contagion". The infectivity of GPL can be divided into horizontal infection and vertical infection. Vertical infection is directly modified in the source code of GPL, and the modified program should be open source according to the requirements of GPL protocol. Horizontal infection is that the program uses GPL source code or GPL source code fragments, and the parts using GPL code and derivative parts should be open source according to the requirements of GPL protocol.

If the above-mentioned licensees violate the GPL agreement, they may not copy, modify, sublicensee or distribute the open source software. Any attempt to copy, modify, sublicense or distribute the Program in any other way shall be null and void and shall automatically terminate the rights based on such authorization.

At present, the mainstream practical view in China holds that the legal nature of GPL agreement is a copyright contract with rescission conditions, which should be adjusted by the Civil Code and the Copyright Law. The license terms in the agreement are the conditions of the copyright license. If the user violates the terms, the prerequisites of the license no longer exist, the GPL agreement will terminate and the authorization obtained by the user will automatically terminate.

The Guangzhou Intellectual Property Court first made a clear response to the legal nature and validity of the GPL agreement in judicial practice. Taking the GPLv3 agreement involved in the case before it as an example, the court held that:First, the content of the GPL agreement has contractual characteristics.The GPL3.0 agreement belongs to the meaning expression of private law effect, and the meaning expression is the core element of civil legal act, so the GPL3.0 agreement is a kind of civil legal act. The agreement grants users the rights to copy, modify and republish, which in fact forms a change of rights between the authorized person and the user, which belongs to the civil legal act of establishing, changing and terminating the relationship of civil rights and obligations. The rights licensed by the licensor comply with the relevant provisions of my country's copyright law; it uses an open source license to publish source code and grants most of its copyrights to unspecified users, which is completely voluntary. Users copy, modify or redistribute the source code under the license, and make commitments to the license by behavior, which is also voluntary. The license is established when the user copies, modifies or publishes the source code, and the license has legal effect.Second, the form of the agreement also has contractual characteristics.The GPL3.0 agreement expresses its content in electronic text, which is a tangible form of expression and belongs to a contract concluded in written form. In summary, the GPL3.0 agreement is contractual in nature and can be identified as a copyright agreement between the authorized person and the user, which falls within the scope of the legal adjustment of China's contract.

On the infringement liability for violation of GPL3.0 agreement: in order to protect the exclusive rights of the obligee, the copyright law only stipulates that the non-obligee can use the work within the scope of "reasonable use", while the rights such as copying, modifying and distributing belong to the obligee. Anyone who commits these acts without permission will constitute infringement. According to Article 8 "termination of authorization" of GPL3.0 agreement, the licensor permits the user to exercise certain rights under the premise of complying with the provisions of the license, but the user must bear the corresponding obligations.If a user copies, modifies or disseminates a protected work in violation of the conditions of use of the GPL3.0 agreement, the license obtained through the GPL3.0 agreement will automatically terminate.In this regard, China's law on conditional civil juristic acts provides that "civil juristic acts may be conditional ...... civil juristic acts with conditions of discharge shall expire when the conditions are fulfilled". According to the characteristics of open source software, the conditions of use stipulated in the GPL3.0 agreement (such as open source code, marked copyright information and modification information, etc.) are the prerequisites for the licensee to permit the user to use freely, that is, the release conditions attached to the agreement. Once the user violates the preconditions of use, the GPL3.0 agreement will be automatically released between the licensor and the user, and the license obtained by the user based on the agreement will be terminated immediately. The user's copying, modification, publishing and other acts constitute infringement due to the loss of the source of rights.

Clarifying the legal liability for infringement of open source software licenses can, on the one hand, stop the infringement in time and prevent the improper use of open source software by others; on the other hand, it can effectively protect the interests of the authorized person, so that they can retain the motivation to continue to create, and promote Source code sharing and knowledge dissemination.

The court that responded to this question was the Guangzhou Intellectual Property Court,The court held that developers could not include a reservation of commercial use in the GPL agreement because the reservation of commercial use contradicted the "Copyleft" nature of the GPL agreement and should be a non-permissive additional clause.The following is an example of the GPLv3 protocol:

GPLv3 ProtocolArticle 5Provisions: Regardless of how the Software is grouped together, you must license the entire Software to the person who wants to license it in accordance with this Agreement, and this Agreement and the additional terms that comply with Section 7 apply to the entire Software and each part thereof. The AgreementArticle 7Provisions: ② When you publish a copy of a protected work, you can optionally remove additional terms from the copy or parts of it (additional terms can require that they be removed under certain circumstances when you modify the program). In protected works for which you own or are able to grant appropriate copyright licenses, you may attach a license to the material you add. Notwithstanding any other provision of this Agreement, you may (if you are authorized by the copyright holder of the material) supplement this Agreement with respect to any material you add to the Protected Work with the following provisions: a) indicate that you do not provide warranty liability or limit liability in a manner different from that provided in Section 15 or 16 of this Agreement; or B) require that certain reasonable legal notices or authorship be retained in this material or in a procedure containing appropriate legal notices; or c) prohibit misrepresentation of the source of the material, or require reasonable labeling modifications to be different from the original; or d) restrict the name of the author or authorized person using the material for publicity purposes; or e) reduce the authorization level to use the trade name, trade mark or service mark under the trademark law; or f) require any person who publishes the material (or its modified version) and provides the recipient with a contractual liability promise that such promise will not cause joint and several liability to the author or authorized person. All other non-permissive additional provisions are deemed to be "further restrictions" within the meaning of Article 10 ". If you receive the Program, or portions thereof, that purport to be bound by this Agreement and are supplemented by such further restrictive provisions, you may remove those provisions. The AgreementArticle 10Provisions: ② You may not impose further restrictions on the exercise of the rights granted or recognized in this Agreement.

As can be seen from the above agreement,The biggest difference between open source software and commercial software is that the author of open source software cedes all the property rights of his works to the user, and open source software is a software development model in the form of giving up copyright-related rights. Although the authors of open source software cede their copyright property rights to software users, they have not given up promoting the development of the open source software industry in a commercial way. Open source software does not mean that there can be no commercial development.

The preamble to the GPLV3 agreement states that the so-called free software emphasizes freedom, not free price. The GPLV3 agreement is designed to ensure that developers have the freedom to distribute copies of free software (if developers wish, they can charge for this service). This shows that open source software can still be used in commercial operation mode, but it is not treated as a commodity in itself, but all commercial operations are actually carried out around the derivative products of open source software, such as software support, software services, integration of open source software innovation, development of value-added products based on open source software, etc. The Open Source Initiative (OpenSourceInitiative)'s 10 definitions of open source software include "non-discrimination in any area", such as not stipulating that software cannot be used for commercial purposes. In the process of commercial development, the choice of profit model of open source software is limited by the open source license agreement. With different license agreements, developers or companies have different control over the source code of the project, and therefore can provide different services. Commercial software generally benefits from controlling the software source code and selling software licenses. The profit model of open source software is diverse, mainly through the commercial service model to obtain commercial benefits. The common profit models of open source software include: hardware bundling, value-added products, technical support, advertising business, etc. Enterprises find the right business model for open source software and benefit from participating in open source, which is the driving force for enterprises to support open source for a long time and the basis for the long-term prosperity of the open source community.

The GPLv3 agreement is a Copyleft license agreement for software and other works, so that the software can be used freely. The GPLv3 protocol guarantees users the freedom to share and modify full versions of a program, so that the software remains free for all users. In the program developed by the developer based on the GPL, if the commercial use restriction reservation clause is added to restrict the purpose of the user to use the source code, the scope of the user will also be restricted, that is, only non-commercial users can use the source code, which obviously contradicts the "Copyleft" feature of the GPLv3 protocol. The restriction clause is also not one of the six supplementary clauses that can be added under Article 7. It should be a non-permissible additional clause and belong to the "further restriction" under Article 10. Therefore, developers have no right to add a commercial use restriction clause to program items applicable to GPLv3 agreement. Subsequent programs developed again based on the source code need not follow the restriction clause.

The question of whether the accused infringer's defense of open source code can be established can be referred to the views of the Supreme People's Court in the (2019) Supreme Law Zhimin Zhong No. 663 civil judgment.

In the case of (2019) Supreme Court Zhimin Zhong No. 663, the accused infringer and the plaintiff jointly confirmed that the front-end code of the plaintiff's website used the open source code under the GPL license agreement. According to the alleged infringer, the plaintiff used the open source code applicable to the GPLv2 software license agreement. According to the relevant contents of the GPL license agreement, the plaintiff has no right to claim copyright on the entire software of its website. In this regard, the court held that the code of the plaintiff's claim was the back-end code. Front-end code development mainly refers to an implementation of page design for operation interfaces visible to front-end users, such as page layout and interactive effects, while back-end code development mainly refers to the implementation of modules such as server-related logic functions invisible to back-end users. The two are independent programs with different display methods, different technologies and obvious differences in division of labor. According to the relevant provisions of the GPL agreement, the licensed object of the GPL agreement is the copyrighted program approved under the GPL agreement license and the derivative or revised version based on the program. As far as this case is concerned, the open source code has been excluded from the back-end code of the right claimed by the plaintiff. Although the plaintiff used the open source code in its front-end code, its back-end code program is not a derivative or revised version of its front-end program. Therefore, according to the relevant provisions of the GPL agreement, the agreement has no binding force on the code involved. Accordingly, the relevant defense of the accused infringer cannot be established.

In reference to practice, in order to solve the problem that the GPL agreement is too strict, the Android operating system released by Google divides the system into multiple independent different levels of framework, and applies different open source license agreements to each level. Google uses the open source Linux kernel that follows the GPL license agreement in the kernel of the Android operating system, so the application software developed by individuals or enterprises for the Android system must also be disclosed in accordance with the GPL, which will seriously reduce the enthusiasm of enterprises and individual developers to participate in the development of the Android system and hinder the establishment of the entire open source operating system ecological environment. In order to solve this problem, Google limited the application of GPL to the independent underlying Linux kernel space of Android system, while the more relaxed ASL open source software license agreement was applied to the upper class library and application framework and user space. Since the upper class library, application framework and user space are not regarded as derivatives of the underlying Linux kernel, GPL license agreement is avoided to infect the entire Android system, so the hardware driver and application framework program in the upper layer of Android system are independent, and its developers apply ASL for development and can freely choose whether to disclose their source code.

From the above, it can be seen that even if developers use open source code based on GPL protocol in front-end code, if they can prove that the back-end code program is not a derivative or revised version of its front-end program, and the front-end and back-end codes are independent of each other, then the back-end code does not need to be restricted by GPL protocol and does not need to be open source.

However, it should be noted that if the accused infringer fails to prove that the GPL open source code he uses is independent, or applies different open source license licenses in each independent different level framework, he shall bear the burden of proof. The program based on the secondary development of GPL protocol code shall follow the GPL protocol as a whole. If it does not provide the source code to the user, its behavior violates the provisions of GPL. GPL agreement automatically terminated, its behavior should constitute infringement.

According to the court's trial thinking, the method of judging whether the accused infringing work has used the copyright work is generally applicable to "contact plus substantial similarity" in copyright infringement cases ".

With regard to the possibility of contact, it is generally judged whether the accused infringer has the possibility of contacting the plaintiff's earlier issued procedure. As for substantial similarity, based on the comparison results and technical analysis, decompile the secondary development software based on GPL protocol that has been sued for infringement, obtain the source code, manually compare it with the original software source code involved in the case, count the similar lines, and check whether there are many parts of the program files with sampling ratio that are substantially the same in terms of program logic and structure, and whether the naming characteristics of function variables are the same or similar, whether the GUID, third-party program selection applies, random numbers, writing (including comments) defects, errors, etc. are the same or similar. In particular, writing errors in the code, in general, the probability of the same writing error or comment error occurring multiple times in the code in two programs that do not have substantial similarity is extremely low, so the same writing error is more helpful to determine whether there is substantial similarity.

According to the comprehensive analysis of the above judgment methods, it can be concluded whether there is substantial similarity between the secondary development software and the original software based on the GPL agreement and the proportion of substantial similarity. If the proportion is higher, it constitutes substantial similarity, and the secondary developer (the accused infringer) should bear the legal responsibility of stopping the infringement and compensating for the losses.