Since 1978, Copyright exists as soon as you express your original idea onto some tangible medium. Much of the difficulty with copyright law centers around the investigation into whether or not a particular work is subject to a copyright. This is particularly true for older works (those created prior to 1978) where copyright duration may depend on whether or not a renewal was sought and the attachment of a copyright may depend upon whether or not the copyright was registered or whether the work was published with notice of the copyright.