Manuel Miranda, who served on Hatch's Judiciary Committee and later as a top adviser on judicial nominations to Senate Majority Leader Bill Frist, said Monday that he filed the lawsuit to end what Miranda maintains is a pointless and overreaching investigation and to try to clear his name.

It would put a stop to the investigation and also declare that I violated no law, Miranda said. Mind you, it's not done frequently because most people [under investigation] like to hide and hope the clouds will pass them by.

In addition to quashing the investigation against him, Miranda said he wants to challenge the standards that allow members of Congress to decide that any document they have should be considered confidential.

The suit was filed in the U.S. District Court for the District of Columbia late Friday and notice was scheduled to be served on the Justice Department on Monday, Miranda said.

Justice Department spokesman Charles Miller said the department would not comment on the lawsuit.

A three-month investigation by the Senate sergeant-at-arms, William Pickle, found that Republican staff downloaded thousands of Democratic files. The aides were able to do so because of gaping holes in computer security.

The matter was referred to the Justice Department for investigation. The case was assigned to David Kelly, the U.S. attorney in New York City.

The documents involved spelled out Democratic strategies for opposing certain nominees, and show that senators wanted to delay certain judges, either to influence the outcome of litigation or to help in party fund-raising.

In his filing, Miranda notes that Hatch and Frist often referenced information contained in the Democratic memos during speeches on the judicial nominees that Miranda wrote on their behalf.

Sen. Hatch is confident the Justice Department will bring the matter to its correct conclusion in a fair and professional manner, said a statement from his office.

In February, Miranda resigned his job in Frist's office. Since then he has been critical of Hatch for allowing the matter to continue.