As mentioned above, for the purposes of the mail fraud statute, it is unnecessary that the defendant himself use the mails, so long as he “causes the mails to be used.” This means simply that use by another is reasonably foreseeable, and includes any mailing incidental to an essential part of the scheme. Perhaps this reveals an explanation for the statute’s wide applicability – the collection and clearance of checks, for example, requires many incidental ordinary business mailings, all of which count for the purposes of “use of the mails” under the mail fraud statute. If the purpose of the scheme is to defraud, it doesn’t matter if the culpable mailing is one required by law. Indeed, an employer is not off the hook if it is his agent that unwittingly mails a document that is incidental to an essential part of the scheme; through vicarious liability he has caused the mailing through his agent.
The mail and wire fraud charges are frequently combined with a conspiracy or accessory count. Since almost any conspiracy is a “scheme to defraud,” if a prosecution can show a use of the mails or wires in connection with the conspiracy then it gains added ammunition. Showing intent to use the mails is always enough without proving actual use, and if use of the mails by another was reasonably foreseeable as incidental to part of the scheme by the perpetrator, depending on the jurisdiction this can also satisfy the mailings element. However, the defendant must be shown to have actual knowledge or awareness of the substantial probability of the use of the mails, not just the general scheme.
It is also important to understand that each use of the mails is a separate and distinct offense. This means that a person convicted of several counts of mail fraud can receive consecutive sentences for each count. While this may seem multiplicitous (certainly to an unlucky defendant), the Supreme Court has noted that use of the mails is the “gist of the crime” in upholding such consecutive sentences. The same idea applies to the wire fraud statute. Moreover, neither the mail nor wire fraud statutes are preempted by subsequently enacted and more specific federal criminal legislation that was designed to deal with special contexts. In other words, when a context-specific consumer fraud statute is passed, the consumer fraud can still be prosecuted under the original mail/wire fraud statute. This allows prosecutors to out-flank both procedural and substantive obstacles found in the subsequent legislation. Perhaps now you can see why the mail and wire fraud statutes are such powerful weapons for federal prosecutors. Indeed, so goes the well-known maxim among federal prosecutors: “When in doubt, charge mail fraud.”