Leaders may choose their friends, but they do not control those friends. And so when those friends make trouble, a leader's first responsibility is not to a friend, but to the organization he leads.

This point is even more operative in the case of allies, be it a country or a company. "Nations do not mistrust each other because they are armed," said Ronald Reagan. "They are armed because they mistrust each other." Allies come together for mutual interest; they are not friends per se; they do things for one another not because they like or even respect the other but because it is in their best interest. Countries get together for trade or protection; companies come together to share technology or even customer knowledge. Allies trust each other so far as mutual interest makes it viable.

Friends, on the other hand, trust each other because they respect and like one another. A friend, wrote Aristotle, is "a single soul dwelling in two bodies." Friends watch one another's back because they want to, not necessarily because they have to.

But leaders must approach friendship with caution. David McClelland, the pioneering organizational behavior theorist, argued that leaders had three key needs: achievement, power and affiliation. Of the three, the first two (power and achievement) are paramount; the third (affiliation) is less so. And for good reason: friendship can make decision-making difficult.

Leaders represent a collection of individuals, not individuals per se so they must do what the organization needs them to do, not necessary what a friend needs. Case in point is a promotion. A leader may be tempted to put a trusted associate into a position of authority, but if that person is not qualified to hold the position then the leader is not acting responsibly; he is putting self interest ahead of organizational interest.

With that understanding in place it is easy to make the case that leaders can and should disassociate themselves from friends who make ethical transgressions. If the leader does not reprimand that individual, or disassociate from that person, then the leader's own judgment is called into question. We have plenty of such examples of executives looking the other way during the recent financial crisis. Senior leaders who ignore an ethical issue are themselves subject to blame.

Another issue arises, and it comes from the best intentions. Good leaders want their people to succeed and so when a subordinate makes a mistake, a good leader will want to help correct the problem. This is good practice when the mistakes involve business or organizational issues, but not when the mistakes involve ethics. Failure to discipline the subordinate risks making the leader appear complicity and perhaps culpable.

Leadership is a judgment call. Make the right calls most of the time and you are leading effectively. Do it less frequently and you fail to inspire trust. And when that occurs, your leadership is over.

First posted WashingtonPost.com/On Leadership 6.01.10