From Cordero v. St. Vincent's Hospital and Medical Center of N.Y., 2008 N.Y. Misc. LEXIS 3315, 239 N.Y.L.J. 102 (Sup. Ct. N.Y. County May 7, 2008):

Spoliation of evidence occurs when "a party alters, loses, or destroys key evidence before it can be examined by the other party's expert..." Squitieri v. City of New York, 248 A.D.2d 201, 202, 669 N.Y.S.2d 589 (1st Dep't 1998). Spoliation was originally limited to the intentional destruction of evidence arising out of a party's bad faith. Kirkland v. New York City Hous. Auth. et al., 236 A.D.2d 170, 173, 666 N.Y.S.2d 609 (1st Dep't 1997). However, spoliation has since been expanded by the courts to include the destruction of evidence based on negligence "since a party's negligent loss of evidence can be just as fatal to the other party's ability to present a defense..." Squitieri at 203, 669 N.Y.S.2d 589. As the Kirkland Court explained, the "trend toward expansion of sanctions for the inadvertent loss of evidence recognizes that such physical evidence often is the most eloquent impartial 'witness' to what really occurred, and further recognizes the resulting unfairness inherent in allowing a party to destroy evidence and then to benefit from that conduct or omission..." 236 A.D.2d at 173 (citation omitted).

In determining what sanctions, if any, should be imposed based on the negligent spoliation of evidence, the courts consider whether a party was on notice of the litigation when the evidence was lost or destroyed, and whether the evidence was critical to a party's proof of the relevant claim.