The profound polarization of American politics in recent years has produced a good many striking phenomena, but few of them as striking, or as damaging, as the disclosure of various government efforts to discover and forestall future terrorist attacks on this country.

The formula is simple. A reporter for one of the many liberal newspapers or TV outlets hostile to the administration develops a similarly minded contact in one of the agencies charged with protecting the country against such attacks. The contact (whom the reporter guarantees against disclosure of his or her identity) tells the reporter about some technique the government is using to try to identify Al Qaeda agents planning mischief. The technique often involves detecting communications between such agents, and therefore must pass the test of not infringing impermissibly on normal communications between innocent American citizens.

The administration knows this, and takes great care to make sure that its surveillance techniques pass that test. Thus, before it taps a communication between any two people in the United States, it applies for a warrant from a special court set up by Congress to pass on such requests. In the case of communications between a person in the United States and a suspected al Qaeda agent abroad, however, the Attorney General has ruled that such a warrant is not required under the law Congress passed. And the government has similarly obtained, and assembled into a vast database, records of the calls made from one telephone number to another in this country -- the same information that is listed in your monthly phone bill, and which the Supreme Court has already ruled is not confidential. (It should be stressed that the calls themselves are not tapped. The government seeks only to know if one phone number is calling another a suspiciously large number of times, or on occasions that appear related to terrorist activities.)

As a final precaution, all such techniques are disclosed, in secret briefings by the Executive branch, to the leaders of both parties in both Houses of Congress, and to the chairmen and ranking opposition members of the intelligence committees of both the House and the Senate.

The editor whose reporter has learned of such a secret operation thereupon splashes it across the front page of his paper, or on his TV network's evening news hour. He will, of course, take care to interview one or more Democratic members of Congress who weren't in on the secret briefings, and they can be depended upon to shriek that every American's privacy is being invaded unconstitutionally by this dastardly administration. (Congressman Harold Ford of Tennessee charged the other day that the government is "eavesdropping" on innocent citizens -- the falsest imaginable accusation.) As for the Democrats who were briefed, they tend to hint that they weren't told "everything," or just prudently keep their mouths shut.

But that's not even the most delicious result of the scam. Dana Priest, a Washington Post reporter, has already received a Pulitzer prize for her report, obtained from a leaker, on the CIA's supposedly "secret" prisons in eastern Europe for top-level Al Qaeda detainees. One wonders if Osama bin Laden has some similar sort of Medal of Honor for American reporters, not to mention CIA agents, who expose our counter-terrorist operations, to his benefit.

The leakers, in any case, have the satisfaction of seeing their vindictive hatred of the Bush administration (whatever its origin -- being passed over for promotion, perhaps?) take the form of political damage it can ill afford.

To be sure, one alleged leaker was caught recently. Mary O. McCarthy, a CIA officer who had contributed the maximum allowed by law to the Kerry campaign in 2004, flunked a lie-detector test and confessed, according to the CIA, that she "knowingly and willfully shared classified intelligence." Later, after consulting a lawyer, she revised her story and denied she had done anything wrong. (One of her media contacts, by the way, was reportedly Dana Priest.)

Thus far has concern for our national security deteriorated, in the eagerness of the Bush administration's enemies to bring it down.