The Electronic Frontier Foundation (EFF) today officially asked all parties involved in the Megaupload criminal case to refrain from deleting any data stored on servers once leased by the file-hosting service—and it suggested it was willing to sue over the matter.

In a letter (PDF) sent to the Eastern Virginia US Attorney's office and to lawyers for Megaupload, the EFF asks for all material on the servers to be retained "both for purposes of contemplated future litigation and as a matter of obligation and courtesy to the innocent individuals whose materials have unfortunately been swept up into this case."

When the government took down Megaupload on January 19 and asked New Zealand to arrest the site's top employees, it did so with no advance warning to people who used Megaupload for entirely legal purposes. As for getting data back now, the government says that it never actually seized the servers in question and that they are back under the control of the hosting company. Because the government seized most Megaupload assets, however, the site can no longer afford to pay for the servers, which could be wiped at any time (the main hosting company, Carpathia, has pledged not to do this without providing advance notice).

"In many instances, this material included protected expression under the First Amendment," says the EFF letter, "which raises additional concerns... We are hopeful that our client and other third parties can obtain access to their material without resorting to legal action, but if that is not the case, we intend to take the necessary steps to ensure the return of their materials."

The letter ends, however, on a more conciliatory note, stressing the EFF's willingness to work with the government to devise a protocol for getting data back to "innocent customers" in these kinds of cases going forward.