28 C.F.R. § 59.1

(a) A search for documentary materials necessarily involves intrusions into personal privacy. First, the privacy of a person's home or office may be breached. Second, the execution of such a search may require examination of private papers within the scope of the search warrant, but not themselves subject to seizure. In addition, where such a search involves intrusions into professional, confidential relationships, the privacy interests of other persons are also implicated.

(b) It is the responsibility of federal officers and employees to recognize the importance of these personal privacy interests, and to protect against unnecessary intrusions. Generally, when documentary materials are held by a disinterested third party, a subpoena, administrative summons, or governmental request will be an effective alternative to the use of a search warrant and will be considerably less intrusive. The purpose of the guidelines set forth in this part is to assure that federal officers and employees do not use search and seizure to obtain documentary materials in the possession of disinterested third parties unless reliance on alternative means would substantially jeopardize their availability (e.g., by creating a risk of destruction, etc.) or usefulness (e.g., by detrimentally delaying the investigation, destroying a chain of custody, etc.). Therefore, the guidelines in this part establish certain criteria and procedural requirements which must be met before a search warrant may be used to obtain documentary materials held by disinterested third parties. The guidelines in this part are not intended to inhibit the use of less intrusive means of obtaining documentary materials such as the use of a subpoena, summons, or formal or informal request.