What are the rights to a song?

Music licensing can be a particularly complex area of copyright law. Hopefully you had some sort of a contract or agreement in place with the artist. If so, you'll need to refer to that contract for your specific legal rights. Absent terms in a contract, the artist-composer maintains the copyright to music (the musical composition). The performers have a copyright in the master recording of the music. This is usually the case with copyright there are two copyrights, one for the music (the musical composition), and one for the performance of the music (the sound recording or "master record"). It's also common for two different entities to own these two different copyrights often the composer and the recording studio, respectively, although the second copyright (the master record) is initially held by the performer you should have a contract in place with your performers making it clear that the copyright for the master record belongs to you. You do need to license the musical composition from the artist. Copyright law has a mechanism called a "compulsory license". The artist cannot refuse your license, but you must pay a statutorily set fee (the amount isn't high). You will pay the artist monthly royalties (set by the statute) based on your sales. Again, this depends on whether you've signed a contract with your artist-composer. You still must abide by the terms of the contract, as must the artist-composer. I hope you also have a contract with your performers assigning the sound recording copyright to you.

A producer contributing an 'appreciable amount' of originality to a recording or musical composition can sometimes be considered a co-author. Put another way, to be able to claim a copyrightable contribution, the producer's particular contributions must have involved an 'appreciable amount' of originality. Of course, vague standards like 'appreciable amount' can result in there being a gray area in terms of whether or not there was an 'appreciable amount' in any given situation, especially if the producer's contributions were relatively small and minor. Also, in the kind of situation you describe, there can be instances in which the session players themselves could also be considered co-authors, unless they signed a work for hire agreement (in which case everything they do at the session would normally be considered work for hire by them, assuming a typical kind of work for hire agreement was signed by them and hence no grounds for them claiming a share of the copyright or ownership.) By the way, the comments above assume that no producer agreement was ever signed or discussed. Typically record producer agreements contain a work for hire clause, saying in effect that the producer's work is 'work for hire' and that the producer won't be considered a co-owner or co-author of such a composition or recording. That is, unless it's a spec deal, in which case the artist and producer might agree to some co-ownership arrangement. One other thing, there is sometimes the issue of whether the producer's contributions could make him or her a co-author of the sound recording and the underlying musical composition or just one of those. The answer depends on the exact nature of the producer's contributions in that particular situation. The above should not be considered legal advice, especially for any particular situation. Without knowing more about the specific of the situation, it is hard to know whether there were particular circumstances, not mentioned in your email, which might affect whether you could legitimately claim to be a co-author.