The Texas Supreme Court recently discussed at length how to use current discovery rules to get electronic data.  In re Weekley Homes, L.P., 295 S.W.3d 309 (Tex. 2009).  However, near the end of the opinion, the Supreme Court stated as follows:

Finally, when determining the means by which the sources should be searched and information produced, direct access to another party's electronic storage devices is discouraged, and courts should be extremely cautious to guard against undue intrusion.

Id., 295 S.W.3d at 322.  This language is unfortunate (and flawed), since there will be many instances in which the best evidence is that which the other party has attempted to delete, erase or "scrub."  Only by access to the hard drives can the data be recovered.  Having access to hard drives to check for deleted data is little different from requesting and obtaining "meta-data" from documents.  Deleted files just have their header deleted or erased.  The files themselves still exist, at leat until overwritten.  The Supreme Court by limiting access to hard drives (or other storage devices) has effectively blocked access to potentially critical data (such as the 22 million emails supposedly lost by the Bush administration and later recovered by Obama administration techs).  This ruling is no different that saying you can have letters from room 1, but not from room 2, since room 2 is "retired" files.  Perhaps in practice, the data will have to be produced, but parties with something to hide on their hard drives will have a handy quote to throw at the trial court to block production.

The better practice would be to require production of the hard drive to a third party expert, with appropriate court orders protecting privacy or trade secret concerns, at the expense of the requesting party.