My understanding of copyright law is that if person or company X is hired to create a program, web site, etc., and there is nothing specifically mentioning ownership of the rights in the contract, then the person or company that hired X owns the rights to the work. Thus, if I hire you to create a web site for me, I own all rights to that site, except for any parts that are copyrighted to someone else already. If the contract between us states that you retain all copyright and intellectual property rights to the code, then I have given up all my rights to modify and do whatever I wish with the code. My only option at that point is to delete it and start over, or get the owner of the IP to modify it.