Lt. Col. Oliver L. North comes finally to the witness stand amid intimations of anticlimax and greatly reduced expectations.

He will not, say all, turn in "the old man" -- his term, according to others, for President Reagan. Taking spears in the chest for the commanding officer is an old Marine tradition.

He will not, say many, tell the truth. The proper young Assistant Attorney General Charles Cooper, who was assigned to find out what went on, says he wouldn't believe him, with or without the oath.

The chore of the members of the congressional select committees is formidable. While not harming North in a personal way, without assaulting the brave Vietnam veteran, the committed cold warrior and the resourceful terrorist-tracker, they must, if the hearings are to have any meaning, bring out the fact that the North brand of patriotism is the unacceptable kind.

The Marine with a chestful of medals is Reagan's "national hero" and may still be one to Americans who agree with North's implicit estimate of congressmen as dolts and diplomats as wimps.

The NSC aide who masterminded the resolution of the TWA hijacking, who set a tail on the terrorists of the Achille Lauro, represents the American ideal of the man of action, admired from Jesse James to Bernhard Goetz.

The current issue of Life magazine features an interview given to "a friend" by North's wife, Betsy. She is as stylized as a Saturday Evening Post cover. She stays home with her children. She sewed her daughter's prom dress, never nagged when her husband came home late. His contra cause is hers: "If you get the true story out," she told Life, "I don't know how people can't see the need to fight back when communism is spreading out."

The accompanying pictures show the earth-shaker as suburbanite, the proud father, the good Great Falls yeoman helping a neighbor mend a fence.

By all accounts, North is a compelling personality, a superachiever with a sense of humor, a boss who set the pace of 14-hour days and never asked anyone to do what he wouldn't do himself -- including shredding classified documents. Iranian-born Albert Hakim, who profited greatly from the arms sales, put it with a Persian poet's excess: He was "dissipating so much love for his country and his associates that the radiation of that love really immediately penetrated to my system."

The committee may want to observe the all-in patriot as pilferer. Inquiries of his occasional dipping into the river of arms-sales gold that flowed through his office might cut down on hero worship. At a time when Elliott Abrams, the State Department's Central America policy leader, told the committee the contras were "starving," North spent $2,449 in contra-provided traveler's checks to buy his own family groceries. He asked for and received from contra leader Adolfo Calero $90,000 of contra funds, and took a $13,900 security system from his pal, retired Air Force major general Richard Secord.

The dangers that an overworked lieutenant colonel subsisting on his Marine Corps pay -- about $50,000 -- could prompt cries for higher military salaries among susceptible members may have diminished. He may have done what he did for his family, but even some of the more incurious might wonder if North okayed his wife's Philadelphia rendezvous with a total stranger who wished to offer her $70,000 because he "loved" her husband.

The paramount issue as defined by the administration is the president's knowledge about the diversion of Iranian profits to contra funds.

It goes far deeper than that. It's a question of who is running the country, of the rule of law, and for that matter, of the Constitution.

If the members concentrate not on North's exploits but his views on those fundamentals, they may be able to make the point that patriotism does not consist of doing what you want, and the hell with Congress.

"Colonel, your motive for helping the contras, when it was against the law, was to bring democracy to Nicaragua. Tell us what democratic government means to you. Do you, for example, believe in majority rule?"

"Do you believe the Founding Fathers were right to divide power between the White House and the Congress?

"Do you believe that the Boland amendment was a law to be obeyed?"

"Do you regard it as your duty to lie for the president?"

"Do you agree with your secretary, Fawn Hall, that 'there are times when you have to go above the written law?' "

"Did it bother you that your courier, Rob Owen, reported that the contra leaders were greedy and corrupt? Did you ever pass on to your superiors and the president reports of contra drug-smuggling? Do you think that could be justified by the fact that they were resisting communism?"

"Who do you think you are?"

"Do you think that any means justifies the end of fighting communism?"