It goes without saying in Washington that a public office is a public trust. We hold our elected officials and their politically appointed minions to higher standards of personal and professional conduct than most of the rest of us would ever dare try to meet.

As far as the voters are concerned, the standard for public officials is not merely that they commit no impropriety, but that they avoid even the appearance of impropriety. That is as it should be: the hint of a scandal is enough to turn an election. Close doesn't count on ethical issues.

The tax shelters used by presidential aides, the sexual behavior of members of Congress, the choice of intoxicants of Capitol Hill functionaries, even an official's decision to drive an imported auto can become legitimate matters of public concern.

The purity we demand seems to decrease directly with distance from power. A member of Congress may beat the rap on drunk driving, but no presidential candidate ever can. What might be intolerable conduct by a Cabinet member becomes an indescretion by a press secretary and simply uncool for a campaign aide.

But a curious phenomena occurs as the concentric circles of accountability spread out in ripples around the White House and the Capitol: At some point on the voyage from public office to private enterprise the waters become so muddied that no one can discern the rules.

We tend to lose track of the public interest implications of the behavior of Washington institutions that are not part of the formal governmental structure.

Nowhere are the ambiguities more difficult--and potentially more dangerous--than in the myriad quasi-governmental organizations and the proliferating private groups that perform public functions.

Conflicts of interest, abuse of office, nepotism and nonperformance can corrupt a government-chartered corporation, a public interest political organization or a nonprofit agency in the same way they undermine a government agency.

Charitable organizations, fund raising foundations, even trade associations play a vital role in shaping our lives, but we rarely hold these groups or their leaders to the high standards demanded of elected or appointed officials.

The issue is abstract, but the hard questions it poses are not. Consider the standards by which we evaluate the performance of the Postal Corporation, Amtrak, the U.S. Synthetic Fuels Corp., the Consumer Co-operative Bank, or the Corporation for Public Broadcasting.

When the mail doesn't come on time or the trains are late, the Post Office and Amtrak take enormous public heat. But the other groups--with similar obligations to the public--are rarely judged by the same rules.

Top brass at the Synfuels Corp. defend their decision to install a sauna in the executive suite. "We're a private corporation and need to offer fringe benefits and pay big salaries to get good people," they claim, that's why some of them earn higher pay than the president's top advisors. The Congress that created Synfuels Corp. doesn't buy that and neither do the few voters who know what the outfit is. But as a government corporation, Synfuels claims exemption from the standards of accountability for elected officials.

The Consumer Co-op Bank was chartered by Congress to finance self-help organizations but has failed miserably at that purpose and almost died aborning due to inept management. Yet its former chief was rewarded with a consulting contract rather than the assignment to Siberia or Sioux Falls that would be appropriate for a failed bureaucrat.

The public interest consideration in judging institutions frequently does not trickle down as far as the public funds that finance them. The near collapse of National Public Radio is rarely discussed as a threat to a public institution or the shortcomings of public servants who ought to be held accountable.

Nor do we often ponder the ethical standards observed by private organizations that routinely funnel ideas and executives into the government, like the American Enterprise Institute, the Brookings Institution and dozens of foundations and trade associations.

There is no consistency in the standards upheld by such groups. On the one hand you have Ralph Nader, who assumes his every personal act will be judged for purity by constituents and foes and who believes that leaders should not profit from the causes. On the other hand are groups like the National Federation for Independent Business which gave its chief executive a three-quarter-million-dollar retirement nest egg last year.

At least one Washington trade association has been run like a family fiefdom, with the top job passed from father to son. And the number of nonprofit organizations that spend the bulk of the budget on executive salaries and fund raising would stun most contributors to such causes.

With no voters who can throw them out of office, no stockholders or members well enough organized to challenge their leadership, the executives of many of Washington's nongovernment institutions are largely insulated from public responsibilities. The time is coming, however, when the public is going to demand that the high standards of elected and appointed offices be observed in other institutions as well.