Copyright Aid

Hi, newbie here. I studied copyright as part of my law studies in the past so, embarrassingly, I should perhaps know this but I'd be grateful for any thoughts/advice.

A firiend and I agreed to collaborate on writing tunes for a production music site of which he is a member. I wrote and orchestrated a tune (using synthesised sounds) and recorded it and sent it to him to add specific sounds that I didn't have. As agreed, he then added percussion sounds (splash and roll type phrases) of his own devising, added a low introductory note, and changed the synthesised sounds I'd used in the tune itself (but not the actual notes). He also mixed/mastered it. This gave us the finished product which we agreed had become a co-composition. (Though we would have split any proceeds 50/50 anyway so this didn't affect that aspect).

Shortly thereafter, for unrelated (copyright) reasons, we agreed not to proceed in partnership. The finished tune is therefore not going anywhere and will only sit on our respective PCs.

My question is, can I now take the tune I originally sent, in its unaltered form (as it was before my friend's contribution) and regard that as mine to do with as I please? My assumption is that I can now take the part I wrote, which, to any practical extent, is the tune, and as long as I don't use any of his contribution, sell it elsewhere. Is that correct?

My apologies for the length of this first post. Thanks in advance for any advice.

I would say your analysis of the situation is entirely correct. The part which you wrote and performed is copyrightable in its own right, and you obviously are the copyright owner of it. As you note, you should avoid incorporating any of the features which your former collaborator wrote/added to the song, but otherwise you should be free to exploit your work as you wish.

Sorry for delay in acknowledging - thanks for the reply, that's reassuring.