Yes, both houses of Congress already have special ethics committees to police the conduct of this nation's lawmakers.

Yes, there are limits to how much can be accomplished by new ethics codes and laws because it's hard for them to cover all circumstances and avoid all loopholes.Yes, this means that the latest efforts to revamp standards of ethics for officials in all three branches of the federal government are still no substitute for a conscience.

Even so, President Bush still did the right thing this week by creating a new commission to recommend tougher ethical standards for government officials. This move sends the country some important signals.

By making this step one of his first acts in office and by putting two prominent federal judges at the helm of the new ethics commission, Bush shows that he considers cleaner government a high priority.

Moreover, by telling the panel to report its recommendations by March 9, the new President is displaying an eagerness for quick accomplishment.

The short timetable raises the question of whether or not Bush is expecting too much, too soon. The deadline is only six weeks away, giving the panel only 30 days after its first meeting to produce a report. Does this mean a slipshod rush jobs?

Not necessarily, since much of the spadework has already been done. The new ethics panel would not have been needed if Ronald Reagan had not vetoed a tough new ethics law from Congress last year. The veto, based on claims that some provisions would make it harder to get accomplished people to serve in top government posts, was an over-reaction.

Anyway, the new panel headed by Malcolm Richard Wilkey and Griffin Bell can simply begin where the recent congressional effort left off. Besides, when it comes to toughening federal ethical codes, some principles should be reasonably clear.

One such principle is that public servants can not serve two masters. This means that members of Congress must stop accepting thousands of dollars, called honoraria, for making speeches or sometimes just for showing up at meetings of special interest groups. The practice looks too much like legalized bribery.

Another principle involves the need for strict limits on how quickly former public servants can cash in on their federal contacts and connections after leaving office. President Reagan was wrong when he objected to a provision that would have required former federal officials and ex-members of Congress to wait a year before becoming Washington lobbyists. A delay of only 12 months would hardly be onerous. Indeed, rather than discouraging public service, a tough measure might simply assure that the government gets the kind of people it needs.

Certainly the need for cleaner government should be beyond dispute. During the previous administration, 125 Reagan appointees were accused of unethical behavior. Former Attorney General Ed Meese was constantly in trouble; only the other day the Justice Department concluded that his conduct should not have been tolerated. Two former White House aides were convicted - Michael Deaver for lying to Congress, and Lynn Nofziger for illegally lobbying his former colleagues.

Despite that sorry situation, Congress is in no position to throw rocks at the White House. Rep. Mario Biaggi of New York was convicted of accepting Florida vacations. House Speaker Jim Wright has been accused of six counts of abusing his office for financial gain and improperly intervening with federal regulators on behalf of his constituents.

The work of the new ethics commission can be relatively simple if its members keep one overriding principle firmly in mind. That principle: When federal officials make decisions, they should be thinking only of the public. Not special interest groups. Not campaign contributors. Not past or future employers. Only the public.

The great majority of public servants already know this. They are honorable people doing honest work. And their reputations unfairly suffer when a comparatively few of their associates get in big trouble. The challenge now is to make the guidelines so clear and firm that only the most obtuse or the most recklessly greedy won't make the right choices.