From Trustees of Chi. Plastering Institute v. Village of Elwood, 2009 U.S. Dist. LEXIS 42952 (N.D. Ill. May 20, 2009):

Defendant hired an expert who admitted at her deposition that there were wiping programs installed on computers belonging to defendant Alberts and Donchez. She also admitted in her deposition that she could not ascertain for certain whether the wiping programs had been utilized before she imaged the computers in May of 2007, several months after the request to preserve the information had been made by plaintiffs. She did state, however, that Donchez' and Albert's hard drives had been "defragged" prior to the imaging process which would have destroyed any evidence of a deliberate effort to wipe the computers. Both Forster and plaintiffs' expert, Dr. Saperstein, discussed a process called defragmentation which automatically rearranges files on a hard drive so that they are contiguous. This causes existing data to be moved and re-written to the surface of a hard drive. Empty spaces, which would occur when files were deleted, automatically would be overwritten by this data. Once defragmentation occurs, it is impossible to determine whether files were deleted to a certainty. The record shows that the Donchez and Albert computers were defragged many times after the preservation notice was sent to defendants and even after the agreement to image the hard drives had been reached.

Defendants do not dispute these facts. *** But they contend because "routine defragmentation and wiping" has resulted in the destruction of some relevant documents, particularly on those computers that they failed to image in their initial production, they should not be sanctioned, citing Wiginton v. CB Richard Ellis, 02 C 6832, 2003 U.S. Dist. LEXIS 19128, 2003 WL 22439865 (N.D. Ill. October 27, 2003). But defendants clearly fail to comprehend the holding of that case. The court in Wiginton excused the destruction of documents when it was pursuant to a routine document retention policy and when it was prior to notice of the need to retain those documents. But the court found sanctionable the failing to preserve documents scheduled for destruction, pursuant to an established policy, after the parties were on notice that the documents were discoverable. "At that point, " the court wrote, "we must find the reason for the destruction becomes because the party knew that relevant evidence was contained in the documents and wanted to hide the adverse information, rather than because the documents were scheduled to be destroyed." 2003 U.S. Dist. LEXIS 19128, [WL] at *7. Even assuming that the destruction of relevant information was accidental, as defendants argue, there is ample evidence in this record to find that the failure to preserve ESI in this case was reckless and that defendants are at fault as the Seventh Circuit has defined that term. In addition, there is, in the testimony of Officer Lightfoot and Brandon Doden, some evidence in this record that the hard drives of certain of the computers were deliberately wiped.

Defendants nevertheless argue that plaintiffs are not prejudiced because they cannot point to any "missing" documents. Defendants claim that the dearth of ESI is simply because there were few e-mails or other documents that were responsive to discovery requests. Putting aside the fact that it is impossible for plaintiffs to know what evidence was destroyed unless they are clairvoyant, Dr. Saperstein had identified several e-mail "chains" in which it is clear that some of the e-mails referred to are missing, suggesting that relevant documents were destroyed accidentally, if not intentionally.