The Federal Rules of
Discovery (some States are also follow similar rules)
dictate that each company has a duty to preserve
documents that may be relevant in a case.
"When duty to preserve
is triggered, promptly isolate and protect potentially
relevant data in ways that are: legally defensible;
reasonable; proportionate; efficient; auditable; broad
but tailored; mitigate risks" (source edrm.net).
An employee left the
company? are you are upgrading/changing computers? It's
best to preserve electronically stored information
that's legally defensible especially if its hidden in
unallocated space, File Slack Space, or in the Windows
swap file. You never know if and when you'll need it.