Fifth Circuit rules that Vaughn Index is necessary to withhold documents

02/27/10: The FOIA blog reports that the United States Court of Appeals for the Fifth Circuit has ruled that the IRS did not adequately explain its witholdings and must provide a Vaughn index when in litigation before it can have a Court rule that it properly withheld documents.  The Court explained in detail why a Vaughn index or a similar document that specifically explains why documents have been withheld are necessary.