Outsiders, and some Americans as well, may be puzzled by what has been happening over this past week in Washington, where most of the people in and around government watched and listened day after day to a battle of lawyers in a committee room on Capitol Hill. To understand this, it is helpful to remember a practice of the ancient Romans. When one of their generals returned from some far-off conquest, he was granted a triumphal procession through Rome. But as he rode through the cheering throngs, a slave stood behind him, whispering over and over again into his ear an injunction: Remember, you too are mortal.
Different people in different ways try to curb the arrogance of power on the part of their leaders. The American way of doing this is through hearings on Capitol Hill, where the doings of the chosen leader, in this case called a President, are subjected to intensive scrutiny in a manner that has the immediate effect of slowing the governance of the country and putting new restraints on the power of initiative of the President.
The central figure in the committee room on the Hill was Oliver North, a lieutenant colonel in the United States Marine Corps. But the real question was whether information could be extracted from him which would implicate President Reagan in past behavior that stretched or possibly even violated what was then the law of the land.
In reality, this is an oblique attack on the interventionist foreign policy that Mr. Reagan has practiced off and on throughout his presidency. What it does, no matter what Colonel North may or may not disclose, is to put fresh restraints on the President's freedom of initiative.
It is probably not going to stop Mr. Reagan's latest ``forward'' policy of putting the American flag on 11 Kuwaiti tankers for the larger purpose of asserting US naval primacy in the Persian Gulf. Leaders of the Democratic Party have concluded that, because the operation has been advertised and launched, there would be more danger in calling it off than in allowing it to go ahead.
But the net effect will be at least to make Mr. Reagan more cautious the next time he wants to use the armed forces of the United States in a forward or interventionist manner. It may cause him to take counsel of the leaders of the Congress before acting, rather than acting without telling them, as he did in the case of the attempt to trade arms for hostages with Iran.
Another effect may show up in the matter of support for the contra rebels of Nicaragua. Mr. Reagan clings to that policy. It is too soon to be sure whether he will be granted more funds for another year of contra campouts in the rain forests of Nicaragua.
Other peoples use different methods of curbing their leaders. The French cut President Fran,cois Mitterrand down by simply giving the party of his right-wing opponents a majority in the Chamber of Deputies. The British do it by question time in Parliament, and the always-present threat of a vote of no-confidence. The Americans, with no provision in the Constitution for an executive directly responsible to the Congress, do it by summoning the executor of presidential policy to the hearing room.
Colonel North was an executor of two presidential policies that were mixed together. One was the policy of trying to extract hostages from the Middle East by selling arms to Iran. The other was to support the contras in Nicaragua. Profits from one were funneled into the other.
The resulting double operation was intended to be covert. The launching of such a clandestine operation was in itself an example of presidential pride of power. It reflected a tendency that has beset more than one presidency to believe that it is permissible for a president to bend or break the law simply because, being president, he considers himself the law.
It was once an axiom of British law that ``the King can do no wrong.'' Then the time came when King Charles I paid with his life for believing that axiom to be literally true. Since then, British monarchs have been personally subject to the law. Mr. Reagan in Washington is going through the painful process of learning that he, too, can be restrained.
Outsiders should not make the mistake of thinking that this affair of Colonel North may end like Watergate in the resignation of a President. That outcome is conceivable, but unlikely.
The opposition in the Congress is not trying to bring Mr. Reagan down. It is trying to set up effective restraints on his practice of foreign policy.