In Solow v. Aspect Resources, LLC,  2008 WL 441394 (Del. Ch., Feb. 8, 2008), read opinion here , the Chancery Court in a one page letter addressed the enforceability of a subpoena. The decision is so short that it would be easier to quote it than to summarize it. Here is the text of the letter to counsel:

Counsel for non-party Noble Energy, Inc. (“Noble”) is hereby directed to submit information
regarding the eDiscovery qualifications of Holden Chang, the information technology consultant Noble stated it utilized in conjunction with producing the discovery compelled pursuant to this Court’s October 30, 2007 Opinion and Order. Should Noble fail to timely comply with this directive, the Court will deem Noble’s noncompliance as abandonment of its application for a declaration of compliance with the subpoena and for expenses and will deny all relief sought therein.

Here is a prior decision in the same case enforcing a subpoena on a third-party for eDiscovery.