The modern stage of development of creativity is characterized by an increase in the manufacturability of this type of activity. The art of making popular music fits into this trend, highlighting its advantages and disadvantages most vividly. The peculiarity of popular music production is the repetition of standard expressive means, which have proven to be attractive. The copying of popular fragments and spectacular musical techniques became widespread, resulting in the formation of sound remix culture. Against this background, the number of disputes over the boundaries of legal borrowing of musical material has increased in the courts of the world. In the media sphere, examples of unlawful appropriation of fragments from popular songs that violate the rights of their composers, performers, and producers of phonograms are discussed. To resolve such disputes, specialized procedures have been developed in the world, the results of which are criticized. This article discusses various approaches to the legal qualification of copying musical material. The phenomenon of the formation of musical standards, repetitive elements, techniques, and clichés, which are proposed to be classified as unguarded musical ideas at the doctrinal level, is investigated. The methods used to establish copyright infringement, to identify the facts of unlawful appropriation of musical material, and significant similarity of works are analyzed. Our attention is drawn to the test of the unique quality of a musical work and its justification from the point of view of the principles of copyright. To make decisions on music copying cases, we propose to use data on the quantitative ratio of protected and unprotected material in the compared works, as well as on the sources of borrowing that can be obtained using computer music recognition tools.