On March 1, 1967, the House shut its doors on Rep. Adam Clayton Powell (D-N.Y.). It refused to seat the flamboyant Harlem Democrat because of his misuse of public funds.

The next month, as a hurried afterthought, it voted 400 to 0 to set up a permanent ethics committee in an effort to show that it was not going to apply one standard to Powell, in his prime the best-known black politician in America, and another to the rest of the House.

The committee has never been so hard on anyone since. Now, 20 years later, the panel is widely charged with shirking its responsibilities in the face of repeated instances of congressional misconduct.

Two cases are expected to come up this week that the House Committee on Standards of Official Conduct -- the word "ethics" was dropped from the proposed title the day it was created -- could find all the more difficult to handle because of the criticisms. If it gets tough, the committee will be accused of picking on "scapegoats" to quiet detractors. If it proves forgiving, it will be assailed for conducting the usual whitewash.

"No matter what they do now, there are going to be accusations flying," says Norman Ornstein, a congressional expert with the American Enterprise Institute. "Whenever a case comes up, you're damned if you do and damned if you don't, unless there is an overwhelming consensus about the enormity of the offense. It's a difficult position to be in."

The first case is that of Rep. Austin J. Murphy (D-Pa.), a five-term member from Monongahela, far from the upper rungs of the Democratic power structure. He has been accused of "ghost voting" when he was out of town by having colleagues insert his voting card in the House's electronic tally machine, diverting congressional office supplies and phone service to his former western Pennsylvania law firm, and knowingly keeping a "no-show" worker on a House subcommittee payroll.

The charges, extracted from a report in The Washington Times last May, served as the basis for a trial-like "disciplinary hearing" that the committee began behind closed doors last month. It is the first such proceeding the ethics panel has held in seven years.

The committee is expected to decide today whether the charges against Murphy have been "clearly and convincingly" established, the necessary prelude to a penalty phase at which it would vote on what sanctions, if any, it should recommend to the House.

The second case involves Rep. Mario Biaggi (D-N.Y.), who was sentenced to 2 1/2 years in prison and fined $500,000 last month following conviction for accepting illegal gratuities from a Brooklyn Democratic leader and for trying to obstruct justice in a federal grand jury investigation of their activities.

The House committee has concluded from the trial record that Biaggi "discredited the House of Representatives as an institution" and violated other House rules and codes by his conduct. The next step, which could come this week, will be to determine what penalty -- expulsion, censure, reprimand, fine, loss of seniority -- to recommend, if any.

Biaggi, in his 10th term, faces another criminal trial in New York next month, on racketeering charges in the Wedtech scandal.

Whatever happens to Murphy and Biaggi, critics say, will only serve to underscore what hasn't happened to prominent members of the House Democratic hierarchy whose conduct has been questioned in recent months. The lists vary according to the compiler, but they include House Speaker Jim Wright (D-Tex.); House Majority Whip Tony Coelho (D-Calif.); Rep. Mary Rose Oakar (D-Ohio), vice chair of the Democratic Caucus, and Rep. Fernand J. St Germain (D-R.I.), chairman of the House Banking, Finance and Urban Affairs Committee.

The uproar comes from different directions: public interest groups, newspaper editorials and a contingent of conservative House Republicans who appear consigned to permanent minority status.

"Partly it comes from a deep-felt concern for the morality and ethics of the House but part of it is politics, too," Ornstein says. "We have had Democrats working hard to make this an issue, pointing to many examples in the Reagan administration. Now you have Republicans trying to turn the issue around and put the Democrats on the defensive. The Republicans see Ronald Reagan approaching the end of his presidency, they have few realistic prospects of gaining a majority and they have a new speaker whom they think they can provoke more than his predecessor. This is a good way to push Jim Wright's 'Hot' button."

Whatever their motives, the faultfinders contend the facts are on their side.

"The House ethics committee has repeatedly failed to act in a timely manner and failed, time and again, to recommend sanctions for clear ethical violations, seriously undermining the integrity and credibility of the House of Representatives," says Fred Wertheimer, president of Common Cause, the self-styled citizens' lobby.

Among the cases he cites are those of St Germain, Oakar and former House member Bill Boner (D-Tenn.).

After a 14-month investigation, the ethics panel found that St Germain had violated House rules in understating his assets by more than $1 million and in accepting free jet flights from a Florida savings and loan association, but it recommended no penalties. St Germain, who last month reportedly agreed to buy a Gothic mansion in Newport, R.I., for $800,000, is under investigation by the Justice Department, apparently because of allegations that he accepted food, drink and other gifts from financial industry lobbyists. The ethics committee did not investigate St Germain's entertainment expenses.

Oakar was held to be in violation of "House regulation and law" for paying an aide $47,000 in salary after the assistant, a former housemate, had moved to New York City. Oakar agreed to repay the money and the committee saw no need for sanctions. Oakar also had given a $10,000 raise to another staff member around the same time that they purchased a Washington town house together; the panel saw nothing wrong with that.

Boner came under scrutiny in early 1986 after a defense contractor said he bribed the congressman by paying Boner's wife, Betty, $50,000 in legal fees for work she never did in return for Boner's help on defense contracts. Other charges involved alleged misuse of campaign funds for personal benefit. The ethics committee took no action for 20 months. Boner, meanwhile, was reelected to the House in November 1986 and won election this fall as mayor of Nashville. He resigned his House seat in October, with still no word from the committee.

"The only conclusion that can be drawn from this is that the ethics committee intentionally ducked its fundamental responsibilities, sending a public message that House rules and official standards can be violated with impunity," Wertheimer wrote in the current issue of Common Cause magazine.

Late yesterday afternoon, the committee released a 699-page staff report saying that Boner, in the staff's view, had violated some House rules in using campaign funds for a trip to Hong Kong, for instance, and that his dealings with the defense contractor could be construed "as influencing the performance of his {Boner's} governmental duties."

The report noted, however, that the investigation had not been completed before "the committee lost jurisdiction" over Boner and that if he were still a House member, he would have been given an opportunity to respond to the staff's conclusions.

Another critic of the ethics panel, Rep. Newt Gingrich (R-Ga.) says he is convinced that "you now have a House where it is more dangerous to be aggressive about honesty than it is to be mildly corrupt . . . . We now have in Wright, {House Majority Leader Thomas S.} Foley and Coelho a third generation of Democratic leaders, the first that has never served in a minority . . . . You now have a situation where I think people feel almost invulnerable."

Gingrich is one of four GOP conservatives who have been pressing unsuccessfully for appointment of a special bipartisan commission to look into several specific ethics cases and to help revise the way the House polices itself. He said he is also inclined to think a select committee should be appointed to investigate Wright. "The conduct of the man who is {behind the vice president} in line to be president is as important as Gary Hart's sex life or Joe Biden's plagiarism," Gingrich says.

Wright has come under criticism for his intervention with federal regulators on behalf of Texas savings and loan associations; his receipt in 1986 of dividends and loans from a company co-owned by a Fort Worth developer; and his receipt of 55 percent "royalties" on a book published by a longtime friend whose printing company worked for Wright's campaign committee.

Majority Whip Coelho acknowledged in July that his reelection committee and the Democratic Congressional Campaign Committee, of which he had been chairman for six years, improperly used a Washington-based yacht and airplane for fund-raising events without paying the owner, one of the same Texas S&L's Wright had gone to bat for. The two committees reimbursed the savings and loan $48,000. The ethics panel had nothing to say.

The chairman of the ethics committee, Rep. Julian C. Dixon (D-Calif.), denies that his panel, six Democrats and six Republicans, has fallen down on the job. He has said that the committee has been busy in recent years developing a body of case law to deal with different situations and that the rules will be getting tougher, not easier.

Some critics say this is the kind of work that should have been done long ago. Underneath all the recriminations are three points of view: things have really gotten worse; things are actually better and therefore the misdeeds are that much more noticeable; things are about the same as they were when the committee was set up in the wake of Powell's exclusion.

According to Wertheimer and Gingrich, the ethics panel did flex its muscles a few years ago, especially after passage of the 1978 Ethics in Government Act.

"Look at 1980," Gingrich says. "I was a freshman then. We were very tough. We moved to expel Richard Kelly {R-Fla.} from the House Republican Conference because of the Abscam scandal. {Kelly, later convicted of taking $25,000 from an FBI undercover agent, resigned from the conference.} We expelled Ozzie Myers {D-Pa.}. That was the first time the House ever expelled anyone for corruption. It was probably the high-water mark of trying to clean up the House."

Myers, indicted in the Abscam affair, was found guilty in August 1980 of bribery and conspiracy. A videotape showed him taking $50,000 from an FBI agent who told him, "Spend it well." The ethics committee then began its investigation, culminating in Myers' ouster by a House vote of 376 to 30, well above the two-thirds required. He was the first House member to be expelled since the Civil War.

The House, however, didn't wait for a Justice Department investigation, much less indictment and conviction, to ban an unrepentant Powell. It acted on the findings of a select committee that wanted to seat, censure and fine him. Had he been seated, it would have taken a two-thirds vote to expel him. Instead, the House excluded him by a simple majority rule of 248 to 176, an action the Supreme Court later held unconstitutional.

"We have seen some questionable moves recently on the part of members," Ornstein says. "But ironically, we probably have a cleaner political process than we had, say, two or three decades ago. Decades ago, you could walk into a room with a briefcase full of $100 bills, plunk it down and nobody would know about it. There were no rules for disclosure. The success in getting so much disclosure has, I think, cleansed the process and focused much more attention on the dirt."

Wertheimer disagrees. He sees "a corrupt campaign finance system that just keeps getting worse," with political action committee money, honoraria, free trips and junkets getting out of hand. "You combine that with no serious enforcement," Wertheimer says, "and basically, the message is 'everybody can do what they want.' "

There seems to be a growing sense, in any case, that Congress, like any institution, does not do a good job of policing itself and that outside advisers, perhaps appointed by the leadership for fixed terms, would do better.

"In a general way," says Ornstein, "creating an internal body as a means of showing the public that the institution is serious about ethics never works. You create a reaction. The public says, 'Aha, we knew you had a problem.' Then, if you don't do anything, the reaction is, 'Aha, we knew you'd take care of your own.' "