Re: An unfair system
"AFAIK, patents last for 20 years. Music copyrights last for 70 years from death of author. Where's the fairness?"
You are not comparing like with like.
A patent is granted to an inventor to give them exclusive rights in exchange for making the details of the invention public for the benefit of all. This legal protection is granted in recognition of the fact that someone may lose out on the benefits of an invention because the idea could be taken up by other people who are better able to market their product. Famously, the Rubik's Cube was only patented in Hungary and so Professor Rubik recieved very little royalty for his invention. A limit of 20 years is granted to give a reasonably time for the inventor to benefit from it but after this the idea is available to all.
Copyright, on the other hand, is a protection against unauthorised pubishing of someone's work and this varies from one country to another as well as for the type of material. The date of death + 70 years you quote is (as I understand it) for written work in the UK, so it would apply to the actual music of Pink Floyd separate from any recording. Copyright for recorded material is normally from the date of creation, and is 50 years in the UK and 70 years in the US. This is what Cliff Richard was trying to get changed a few years ago because his earlist songs are now becoming public domain.
From what I understand, Pandora are trying to circumvent this copyright protection to avoid paying the royalties to the artists that they are legally entitled to.