The Copyright Term Extension Act (also known as the Sonny Bono Copyright Act or the Mickey Mouse Protection Act). Basically this law extends the length of copyright terms for plus 20 years beyond what the 1976 Copyright Act had established.

"The Act extended these terms to life of the author plus 70 years and for works of corporate authorship to 120 years after creation or 95 years after publication, whichever endpoint is earlier." - Wikipedia