In Matthew Enterprises v. Chrsyler, No. 13-CV-04236-BLF, 2016 WL 2957133 (N.D. Cal. May 23, 2016), Judge Paul Grewal begins his opinion with a concise and practical overview of Federal Rule of Civil Procedure 37(e):

The rules governing parties’ duties to preserve data do not demand perfection. Only when a party should have preserved electronically stored information “in the anticipation or conduct of litigation” and when that party “failed to take reasonable steps to preserve it” may a court order corrective measures. The standard is an attainable one.