In the U.S., for example, copyright case law contains a substantial similarity requirement to determine whether the work was copied. Likewise, courts may require computer software to pass an Abstraction-Filtration-Comparison test (AFC Test) to determine if it is too abstract to qualify for protection, or too dissimilar to an original work to be considered infringing. Software-related case law has also clarified that the amount of R&D, effort and expense put into a work's creation doesn't affect copyright protection.
Which country needs a similarity requirement to determine if the work was copied?
U.S.