I wrote a joke poem for a friend about a guy we work with, he was never meant to see it, it was as he had written one about me. He stole the poem and photocopied it, altering it, and stating it was a vicious personal attack. He now tries to use it to blackmail me at work to stop him being sacked for incompetence, can he be sued for breach of copyright, and is my poem admissbale as evidence against me for slander if it ever went to court

Did you copyright your work, send in copies to the copyright office, and get it protected, If so, use your receipt from the copyright office and send them a order to stop in their use.

As for the black mail, live up to what you did, since if you did copyright it, it is public record for anyone to see anyway.
And if you do have a copyright, it proves you wrote it, and yes if it does say false things about another person, can be sued as evidence against you.

If it is not copyrighted, then he has to prove you wrote it, but if you did and it tells lies against him, of course he can sue you, if he has actual damages.

If he is using it as blackmail, go to the bosses, and show them what you wrote, so there is no blackmail available.

Well as its mu ip property it doesn't need to be copyrighted under english law. It doesn't say lies about this person it states fact like he dyes his hair, as I said it was meant as a reply to a defamatory poem he wrote about me, I didn't make unproven lies about him, everything written in the poem was based on fact, like he writes poemss submits them on the internet, and then buys the awards from vanity publishers, then goes to local press claiming he has been awarded the trophies. The trouble is I am about to be promoted to one of the bosses, and I have admitted it to my personnel department and my direc tors, I even aplogised that he had taken it the wrong way to him personally and he accepted the apology in front of witnesses, this was over two years ago. Now he has decided that he doesn't want me to move up and is threatening to take the matter higher.