Software Copyright Infringement?

I have been working as an independent IT consultant developing custom software applications. I recently learned that a client is offering to sell one of the applications I developed to another company. They have not discussed this with me nor asked permission. More interesting is the second company originally asked me to sell them my software, then backed out of the deal.

From what I understand of copyright law, the product rights are mine. Every contract I have held with this company has very clearly defined me as a totally independent contractor. I never had a "work for hire" agreement with them, there was/is no written agreement assigning them any rights to products I developed, and my work product doesn't fall into any of the 9 work-for-hire categories. As such, I believe I am the copyright holder with all the rights afforded in Section 106 of the Compyright Act of 1976, which gives the following *exclusive* rights to copyright holders:
- the right to reproduce (copy),
- the right to create derivative works of the original work,
- the right to sell, lease, or rent copies of the work to the public,
- the right to perform the work publicly (if the work is a literary, musical, dramatic, choreographic, pantomime, motion picture, or other audiovisual work), and
- the right to display the work publicly (if the work is a literary, musical, dramatic, choreographic, pantomime, pictorial, graphic, sculptural, motion picture, or other audiovisual work).[3]

I feel like my work is being stolen by my former client. Is this true? Do I have the right to block their sale of the software application I developed?

[annjd]

You often would retain the copyright that is true--but you need to make that clear in your agreement to avoid problems, and make clear what the license they are receiving allows them to do.