Can I use a copy of a signed document in court or am I required to use the original?
Courts normally prefer the original but if you can give a reasonable reason why you do not have it, they wil accept it. If the other side does not object there should be no problem.
The key is why you are not bringing the original to court. There needs to be a good reason.
The "best evidence rule" no longer applies. If you have a copy of a document, and it is clear, it should be admissible, provided that foundation is laid, and the document is properly authenticated.