Because the standards by which copyright infringement are judged are so subjective in nature, each case must be decided on an individual basis. Care must be taken to avoid copying not only the individual components of a pre-existing work, but also the overall appearance of the work as a whole. Whether one piece of music infringes upon another will depend on the facts and circumstances of each case. In one instance, for example, a very popular songwriter infringed a composition written over 15 years earlier by using three notes from the earlier composition. The result cost the songwriter hundreds of thousands of dollars.
Parody is a limited defense.