DMCA The Digital Millennium Copyright Act
The Digital Millennium Copyright Act (DMCA) can be a problem for the preservation of old software as it prohibits required techniques. In October 2003, the US Congress passed 4 clauses to the DMCA which allow for reverse engineering software in case of preservation.
"3. Computer programs and video games distributed in formats that have become obsolete and which require the original media or hardware as a condition of access. ...The register has concluded that to the extent that libraries and archives wish to make preservation copies of published software and video games that were distributed in formats that are (either because the physical medium on which they were distributed is no longer in use or because the use of an obsolete operating system is required), such activity is a non-infringing use covered by section 108(c) of the Copyright Act."
— Exemption to Prohibition on Circumvention of Copyright Protection Systems for Access Control Technologies
In November 2006 the Library of Congress approved an exemption to the DMCA that permits the cracking of copy protection on software no longer being sold or supported by its copyright holder so that they can be archived and preserved without fear of retribution.