The resignation of the Muslim-outreach coordinator for the presidential campaign of senator Barack Obama, Chicago attorney Mazen Asbahi, powerfully reflects two of the biggest obstacles hindering the political integration and empowerment of Arab and Muslim Americans.

This affair demonstrates the external pressures of unfair guilt by association, while at the same time suggesting the internal need for better judgment regarding political and religious actors within the community.

Asbahi resigned on Monday, after just 10 days on the job, because in 2000 he served for a few weeks on the board of an Islamic investment fund with Jamal Said. Said has been allegedly linked to accused fundraisers for Hamas whose recent trial did not result in any convictions, but who remain under a cloud of suspicion.

This reflects an unreasonable and unfair climate of guilt by association. It is part of a familiar pattern that is one of the main forces hindering the political integration of these communities into American civic life.

Asbahi himself is not accused of any misconduct. Rather the issue is his fairly distant association with Said, who himself is disparaged because of the alleged activities of his own associates.

The problem is that almost anyone who has been engaged in Arab or Muslim political affairs can probably be somehow connected in some manner to someone else somewhere whose views, activities or associations can be called into question in the post-9/11 environment.

Call it two or three degrees of separation.

These distant, usually third-party connections are then magnified out of all proportion and used to unfairly impugn or misrepresent the views and character of the person under attack.

Arab and Muslim Americans naturally come into contact with numerous Arabs and Muslims both here at home and overseas. They cannot be reasonably held responsible for views and actions of others of which they were not aware.

Some hostile commentators have perfected the art of seeking out the most distant of such ties to unfairly tarnish the reputations of almost everyone from these communities who has found a political role or voice in our society, including numerous Bush administration officials.

If these are the standards by which Arab and Muslim Americans are to be judged, then only individuals who have been resolutely distant from Middle East and even community-related political activity can survive such judgments. A valuable and significant group of Americans would thereby be frozen out of public life to the grave detriment of our country.

The internal challenge suggested in this affair is that Arab and Muslim Americans have not been vigilant enough about holding political, religious and community figures to reasonable standards of responsible speech and conduct.

Even raising this issue is often seen as too divisive, thereby stifling the conversation and impeding improvement. But solidarity can no longer trump responsibility.

Well-known individuals have been revealed to have deceived the community about their political views and activities, and are nonetheless now being championed as “political prisoners”. Some student groups, especially on the west coast, persist in hosting political and religious extremists as campus speakers. Expressions of religious intolerance too often pass without repudiation. Self-criticism and introspection are distinctly unwelcome in many quarters.

While it is a commonplace of political life that solidarity generally flows from the centre to the extremes, and not the other way around, Arab and Muslim Americans are uniquely unable to afford this under current circumstances.

It is true and irrelevant that toleration of in-group or foreign extremists can be readily identified among many other American ethnic groups, and, indeed, among many of the most virulent individual critics of the Arab and Muslim American communities.

However, the more important reality is that anything that suggests, however inadvertently, sympathy for radicalism in the Islamic world is a uniquely fatal political poison in our country.

While considerable progress has been made, more work is required in developing a consistent and clear consensus among Arab and Muslim Americans setting a reasonable standard of what they, as a community, will regard as responsible and constructive speech and activities.

These need, of course, to be independent, principled judgments, and not simply bowing to external pressures or reproducing bigoted constructs.

But the impulse to reflexively defend marginal figures, actual extremists or religious zealots must be resisted, even when spurred by an understandable sense of loyalty within a community that feels besieged. Raising this issue will itself be seen by some as a breech of solidarity, but recognising and correcting past mistakes is essential.

At the same time, it is unreasonable and unfair to hold respectable Arab and Muslim Americans accountable for the alleged activities of people to whom they are remotely connected by two or three degrees of separation, thereby effectively closing the door to civic engagement on an entire and very significant group of American citizens.