Given the the prominence the press has given to recent cases of copyright infringement (blurred lines) this is an interesting article exploring national anthems, their origins and the various claims of plagiarism.
There is always a possibility that two songs will contain the same sequence of notes at some point, but the number and length of any similarity and being able to demonstrate that there was an opportunity for the author to be influenced by the new song will greatly improve the prospect of a any claim for copyright infringement in the UK.
As the articles demonstrates, this is not a new problem limited to pop songs, but one that has always existed. The difference is that the methods for monitoring releases and identifying similarities in songs are much more sophisticated. Further the resolution of these disputes is now more frequently being made public (through the issuing of court proceedings) rather than settled behind closed doors.
Several of the world’s national anthems are shockingly similar to other compositions. Is this because composers pilfer other people’s tunes – or does it tell us more about the difficulties of writing an original melody