Gauging substantive similarity in software copyright disputes

By Chen Jing, Commerce & Finance Law Offices

Computer software, as scientific works, are protected by copyright laws in countries around the world. Under China’s Regulations for the Protection of Computer Software, computer software includes computer programs and related documents. A computer program refers to a coded command sequence that can be executed, for the purpose of obtaining certain results, by a computer or other information processing devices, or it refers to a symbolised command sequence, or language sequence, that can be automatically converted into a coded command sequence.

Chen Jing
Commerce & Finance Law Offices

Among cases regarding infringement upon computer software copyright, the plaintiff usually claims that the defendant violated the right to reproduce or modify the software concerned, or the right to disseminate it in the information network. To ascertain whether any of those rights of the plaintiff have been infringed by the defendant, a rule known as “contact + substantial similarity + reasonable explanation excluded” is generally employed in judicial practice.

In A Guide for the Trial of Copyright Infringement Cases, released by the Beijing Higher People’s Court in April 2018, the acts to infringe upon computer software copyrights are divided into six types: Mere dissemination; end-user behaviour; plagiarism; destruction of technical measures; rent out; and other infringements.

Guiding cases, or typical cases released by the Supreme People’s Court (SPC) from 2015 to 2019, reveal that all cases involving computer software copyright infringement are of an end-user type, which means the defendant, as the end user, has directly used the plaintiff’s computer software in commercial activities without permission.

As in such cases the defendant seldom makes any changes to the content of the plaintiff’s computer software during the actual use, the focus and difficulty of the trial doesn’t lie in how to determine whether there is substantial similarity between the software products of both sides. However, in plagiarism cases, substantive similarity is usually an unavoidable difficulty in the trial, and a key to affirming infringement.

Judging from cases of software copyright infringement over the years, the court determines whether the software claimed by the plaintiff is substantially similar to that subject to infringement accusation, roughly in the following four directions: (1) the software programs of both parties are substantially similar, for the proportion of same or similar codes in the programs is identified to have reached a certain level, upon comparison of the source code or target code of the two software programs; (2) the software programs are similar as a whole, which means that a comparison of their structures, sequences and organisations verifies that the two are identical or similar in these aspects; (3) it is identified and affirmed that certain content unique to the software claimed by the plaintiff, especially any of its characteristic defects, also exists in the source or target program of the alleged copyright-infringing software; and (4) a conclusion on same or similar software programs is reached on the basis of the results of a software comparison (involving their interfaces, operating parameters, database structure and so on).

Following repeated tests in the trial practice, and thanks to a deepened understanding of the objects under the protection of the copyright law, two out of the above four approaches have gradually dominated the process in determining the substantial similarity of software works, namely the first measure, program code comparison, and the third one, identification of characteristic defects.

In contrast, application of the second approach is decreasing in domestic courts, and employment of the fourth by local courts has been rectified by the Supreme People’s Court. On 20 May 2020, the SPC revised its verdict on a case of computer software copyright infringement by Guangzhou Viska Network Technology and Liu Bin, by revoking the first-instance judgment made by the Guangzhou Intellectual Property Court, and correcting the latter court’s decision that the software programs of the plaintiff and the defendant are substantially similar, a conclusion that had been drawn only on the basis of similarity of such visual content as regarding their operating interfaces and results.

What the copyright law protects is expression, rather than thoughts, which is the fundamental principle of such a law. It indicates that computer software, as a special kind of work, can be protected by the copyright law mainly because the specific instructions and codes used for expression are original. Therefore, it accords with the original intent of the copyright law by comparing the source code or target code of the software programs of both parties to determine whether the two are identical or substantially similar.

However, it’s clear that China’s legislative and judicial circles have not yet provided clear, unified answers to key issues regarding software program codes, including the following points; nor have intellectual property appraisal agencies established operable judgment standards.

Objects for comparison. For example, apart from the source program code, whether the target program code, or the decompiled assembly code of the target program code, can be treated as an object for comparison;

Comparison methods. For example, whether to directly and mechanically compare codes line by line, or rather determine the correspondence between the files contained in the software of both parties, before comparing the lines of code in the corresponding files; and

Standards for judging substantial similarity. For example, whether to employ the data comparison software, Beyond Compare, for mechanical comparison, and determine the proportion of same or substantially similar parts, or, based on the principle of highlighted core functions, to determine that the software programs are substantially similar on the whole, as long as the source codes that reflect the core functions are similar.

The answers to a number of questions, including the above key ones, remain to be studied and discussed by people engaged in related theories and practical applications.

Chen Jing is a partner at Commerce & Finance Law Offices. She can be contacted on +86 10 6569 3399 or by email at