The head of the powerful Senate Judiciary Committee is urging the federal bureaucracy to restore a decade's worth of electronic court documents that were deleted last month from online viewing because of an upgrade to a computer database known as PACER.

Senate Judiciary Committee Chairman Patrick Leahy (D-Vermont) said the removal of the thousands of cases from online review is essentially erasing history.

"Wholesale removal of thousands of cases from PACER, particularly from four of our federal courts of appeals, will severely limit access to information not only for legal practitioners, but also for legal scholars, historians, journalists, and private litigants for whom PACER has become the go-to source for most court filings," Leahy wrote Friday to US District Judge John D. Bates, the director of the Administrative Office of the Courts (AO).

The letter, obtained by The Washington Post, blasted the August 10 decision commencing "without any warning to the public, and without prior notification or consultation with Congress." The letter said that "Given the potential impact of the AO's recent decision, I urge the AO take immediate steps to restore access to these documents."

PACER, which charges 10 cents per page, has long been criticized as a deeply dated system that already does too little and charges too much for online access to things like judicial orders and court briefs.

Affected under the online purge are about a combined decade's worth of court dockets and all manner of documents at the US Courts of Appeals for the 2nd, 7th, 11th, and Federal Circuits, as well as the Bankruptcy Court for the Central District of California. They were maintained on "locally developed legacy case management systems," the AO said, and aren't compatible to be culled into the new PACER system.

The deleted records are available for physical viewing at their respective courthouses in New York City, Chicago, Atlanta, Los Angeles, and Washington, DC.

The most heavily affected court will be the US Court of Appeals for the Federal Circuit, which handles all patent appeals as well as certain other types of cases, like veterans' claims. The Federal Circuit has lost all cases filed prior to March 1, 2012.