On numerous occasions, leaks about U.S. intelligence operations, particularly those against al Qaeda, have damaged our ability to safeguard our nation. They also have endangered the lives of intelligence operatives and informants. So it's hard not to be alarmed by a letter to Congress the Justice Department recently released - a letter indicating that Sen. Patrick J. Leahy, Vermont Democrat, is seeking covert intelligence information.

On March 22, Ronald Weich, assistant attorney general of the Office of Legislative Affairs at Justice, sent Mr. Leahy responses to follow-up questions posed to Attorney General Eric H. Holder Jr. following Mr. Holder's Nov. 18 appearance before the Senate Judiciary Committee. That committee, which Mr. Leahy chairs, normally doesn't deal with classified intelligence information. That's good, because Mr. Leahy's penchant for leaking classified national security information to try to sabotage American foreign policy decisions with which he disagrees has truly made him dangerous to U.S. national security.

In a follow-up question to Mr. Holder after the November hearing, Mr. Leahy complained that he and his House counterpart, Rep. John Conyers, Michigan Democrat, weren't being briefed adequately on the intelligence activities of the FBI. Mr. Leahy insisted that such matters fall within the oversight responsibilities of the House and Senate Judiciary committees. He was willing to "share" oversight with the Intelligence Committees, he said, but the congressional Judiciary committees "should not be shut out" by Justice.

This naked power grab is rather remarkable given Mr. Leahy's demonstrated inability (or unwillingness) to maintain the confidentiality of critical national security information. Mr. Leahy, after all, is the same man who leaked like a sieve during his previous tenure on the Senate Intelligence Committee. The San Diego Tribune, for example, reported that in a 1985 television interview, Mr. Leahy, then vice chairman of the committee, disclosed a top-secret communications intercept of Egyptian President Hosni Mubarak's telephone conversations. The intercept had facilitated the capture of the Arab terrorists who had hijacked the cruise ship Achille Lauro and murdered American citizens. Mr. Leahy's callous disregard for maintaining the secrecy of American intelligence activities ended up costing the life of an Egyptian operative involved in the operation.

In July 1987, The Washington Times reported that Mr. Leahy had disclosed secret information about a 1986 covert operation planned by the Reagan administration to topple Libyan leader Moammar Gadhafi. Federal intelligence officials told the paper that Mr. Leahy had communicated a written threat to expose the operation directly to CIA Director William Casey. Then, just weeks later - surprise, surprise - news of the secret plan turned up in The Washington Post, causing it to be aborted.

Then there is Mr. Leahy's most infamous leak. As the Senate was preparing to hold hearings on the Iran-Contra scandal, Mr. Leahy finally was forced to resign his Intelligence Committee post after he again was caught leaking secret information to a reporter. Incredibly, Mr. Leahy, the ranking Intelligence Committee Democrat, had allowed an NBC reporter to comb through the committee's confidential draft report on the scandal. NBC aired a report based on the inside information on Jan. 11, 1987. Following a six-month internal investigation and after recognizing that investigators had him dead to rights, Mr. Leahy "voluntarily" stepped down from his committee post.

Mr. Leahy's outrageous leak was considered one of the most serious breaches of secrecy in the Intelligence Committee's history. Yet, in his post-resignation statement, Mr. Leahy didn't apologize for compromising national security. Instead, he simply stated that he was angry at himself "for carelessly allowing the press person" to read the report and "to be alone with it." After Mr. Leahy resigned, the Intelligence Committee instituted a new policy that restricted access to its documents to a secure meeting room.

Mr. Leahy has demonstrated time and again that he is not to be trusted with sensitive intelligence information and that he is willing to use it for partisan ends. In fact, he has earned the sobriquet "Leaky Leahy" in the intelligence community. In this dangerous era, with America facing threats from every direction, we cannot afford to allow the senior senator from Vermont to compromise our national security again as he has repeatedly in the past.

In his March 22 response to the Judiciary Committee, Assistant Attorney General Weich seems to rebuff Mr. Leahy's request, saying that while he agrees that Mr. Leahy's committee has oversight jurisdiction over the Justice Department, "certain activities of the FBI are scored to the National Intelligence Program, which we understand falls within the purview of the Intelligence Committees." There is no question that as long as Mr. Leahy remains chairman of the Senate Judiciary Committee, FBI intelligence oversight should be left strictly to the Senate Intelligence Committee - a committee on which Mr. Leahy, given his history of leaks, is no longer welcome.

Hans A. von Spakovsky is a senior legal fellow at the Heritage Foundation and a former Justice Department official.