In 1998, The United States Congress passed the Digital Millennium Copyright Act (DMCA) which criminalizes evasion of copy protection (with certain exceptions), destruction or mismanagement of copyright management information, but includes a clause to exempt ISPs from liability of infringement if one of their subscribers infringes. In addition, the DMCA extends protection to those who copy a program for maintenance, repair or backup as long as these copies are "destroyed in the event that continued possession of the computer program should cease to be rightful."