Here's the source for the data preservation requirement:
http://www.usdoj.gov/criminal/cybercrime/COEFAQs.htm
Preservation is not a new idea; it has been the law in
the United States for nearly five years. 18 U.S.C. 2703(f)
requires an electronic communications service provider to
"take all necessary steps to preserve records and other
evidence in its possession pending the issuance of a court
order or other process" upon "the request of a governmental
entity." This applies in practice only to reasonably small
amounts of specified data identified as relevant to a
particular case where the service provider already has
control over that data. Similarly, as with traditional
subpoena powers, issuance of an order to an individual or
corporation to produce specified data during the course of
an investigation carries with it an obligation not to delete
or destroy information falling within the scope of that
order when that information is in the person’s possession or
control.
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>From the US Code via GPO Access:
http://www.access.gpo.gov/su_docs/aces/aaces002.html
18 USC 2703(f)
(f) Requirement To Preserve Evidence.--
(1) In general.--A provider of wire or electronic
communication services or a remote computing service, upon
the request of a governmental entity, shall take all necessary
steps to preserve records and other evidence in its possession
pending the issuance of a court order or other process.
(2) Period of retention.--Records referred to in paragraph
(1) shall be retained for a period of 90 days, which shall be
extended for an additional 90-day period upon a renewed request
by the governmental entity.
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