WHEN Thomas Jefferson succeeded John Adams, a contest that put America on such a different footing that it is remembered today as the Revolution of 1800, he did not seek to put members of the Adams administration on trial. When Warren G. Harding followed Woodrow Wilson in the White House in 1921, he did not put Edith Galt Wilson on trial for usurping the office of the presidency after Wilson's stroke. When Bill Clinton ended a dozen years of Republican rule in 1993, he did not try to prosecute Ronald Reagan and George H.W. Bush for deceiving the Congress over the Iran-Contra affair.
In the span of 220 years there have been 43 changes of presidents, and always this rule, never written but never broken, has prevailed: Presidents let their predecessors be judged by the merciless jury of history, not by the temporal verdicts of courts.
Commentators and historians often apply a facile shorthand to describe the fundamental principle (and surpassing greatness) of the American political system: Here the transfer of power from one party to another, or from one president to another, is accomplished by ballots, not bullets. That shorthand has an unspoken corollary: Here presidents and parties do not criminalize the policies of their predecessors.
That is why the nascent effort to investigate and perhaps prosecute members of the Bush administration is a dramatic departure from American tradition. It may be true that the Bush administration supported anti-terrorism policies that were deplorable, immoral - and ultimately ineffective. But is the writing of legal briefs on highly controversial, contestable and, even now, unresolved questions of law criminal?
This is no defense of torture nor of the tactics the Bush administration may have used in recent years; press accounts of those episodes that emerged late last month were shocking. But far below the surface of the noisy Washington and cable-television conversation is a quieter but very serious debate, sparked by the circulation in elite legal circles in recent days of an Internet version of a forthcoming article in the Yale Law Journal that argues that "all interrogation methods allegedly authorized since 9/11, with the possible exception of waterboarding, have been authorized before." This article, by William Ranney Levi, is significant as much for its intellectual provenance as it is for its contents. Mr. Levi, part of one of the most distinguished legal families in the nation, exposed his argument to the rigorous review of several leading legal minds, conservative and liberal, some of whom doubtlessly disagree with him.
He cites consultations with Jack L. Goldsmith, the conservative Harvard law professor who resigned from the Bush Justice Department and later expressed qualms over the Bush anti-terrorism legal rationale; Harold H. Koh, the dean of the Yale Law School and a leading human rights activist who has been nominated by Mr. Obama to be legal adviser to the State Department; Mariano-Florentino Cuellar, a Stanford law professor in the Obama inner ring, and Martin S. Lederman, a Georgetown law professor and fierce Bush critic who is the President's choice for a leadership position in the powerful and prestigious Office of Legal Counsel at the Justice Department.
The meaning of all of this is not that the Bush policies were smart, prudent, moral, or effective. They may not have been any of those things. The meaning, however, is that the Bush policies were legally plausible.
That almost isn't the point. The pre-eminent point here is that in the United States, sitting presidents and winning political parties don't sit in legal judgment of their predecessors. If they do not like their policies, and many times they do not, they change policies. They do not sue their predecessors nor seek to punish them legally. This custom has prevailed in times of severe crisis as much as in serene times.
There are myriad examples. Jimmy Carter did not seek to prosecute Henry Kissinger for complicity in the invasion of Cambodia and involvement in Chile, two actions that might be regarded as peculiarly subject to legal review. Richard M. Nixon did not seek to prosecute Lyndon B. Johnson for the illegal wiretapping of Martin Luther King, Jr.'s bathroom and bedroom, which King did not know about until Thurgood Marshall informed him in 1964. Nor did Nixon take any action about the illegal taping of White House conversations in the Johnson years.
In the latter two cases the explanations were political, not legal. The wiretapping of King was conducted on the authority of J. Edgar Hoover, the FBI director whom Nixon dared not alienate. He had to deal with Hoover as well, and he had his own secrets to protect, or soon would. A man who was going to conduct his own taping in the White House was not likely to be predisposed to take legal action against taping by his predecessor.
But in this case, politics is not an insubstantial factor, perhaps for the good of the system. If the Obama team, or the Democrats acting separately from the White House, continue down the road of legal review, they will assure that their successors do the same thing once they are out of office. If you think the politics of 2009 are rough, you will shudder when you contemplate the politics of 2013 or 2017.
"You have to be very careful when and how and what you do in this arena," Democratic Sen. John F. Kerry of Massachusetts, who was separated from the presidency in 2004 by the electoral votes of only Ohio, said in a conversation the other day.
The American system already has a set of checks and balances. It does not need another one. Nor does a president who has vowed a new bipartisanship need a legal inquisition to detract attention from his real priorities, which are his national-security challenges, the economic downturn, education, health care, and climate change. The greatest wisdom on this subject comes from an honorary American. "If the present tries to sit in judgment of the past," Winston Churchill wrote, "it will lose the future."
My guess is that Mr. Obama will call a halt to this or let the natural state of Washington prevail by sitting back and watching while the passions cool and nothing happens.
About six weeks ago, George W. Bush said that he would refrain from criticizing his successor because Mr. Obama "deserves my silence."
Perhaps Mr. Obama, for the good of his own presidency and for the good of the presidency itself, will return the favor.