On September 2, in the midst of the post-Katrina chaos in New Orleans, then FEMA director Michael Brown sent an e-mail to a friend that revealed his state of mind.

"Last hurrah was supposed to have been Labor Day," it said. "I'm trapped now, please rescue me." Brown had planned on resigning his post when the killer hurricane struck, catching him mentally, emotionally and psychologically unprepared. Like the "senior slump" that so frequently strikes capable high-school students once they know that they have been safely embraced by a college and their immediate future is secure, Brown had essentially checked out of his important position well before his departure date. In doing so, he violated numerous ethical duties, most of which can be summarized in three basic principles:

It is undoubtedly bad luck when your biggest job challenge arrives just when your attention, passion, and focus are at their lowest, but what befell Michael Brown (who was not exactly over-qualified for his position on his best days) should serve as a powerful lesson to the rest of us. The duty of diligence demands that you have to be as engaged, industrious and effective in the waning hours of a job as you have ever been. If you don't meet that standard, you are cheating your employer, your colleagues, your subordinates, everyone you serve, and everyone who depends on your performance. And, as Michael Brown now knows, you make yourself vulnerable to a career catastrophe.

For an example of a public servant who appears to be leaving a key position the ethical way, look no further than the U.S. Supreme Court, where Justice Sandra Day O'Connor is committed to staying on the job until her successor is confirmed. That could be a very long time from now, if Senate Democrats decide to filibuster any nominee who won't sing the praises of abortion-on-demand, and if the right wing of the GOP keeps demanding conservative judges who are capable of arguing that the Dred Scott decision was consistent with the Constitution's "original intent." O'Connor is weary and ill, and wants to leave the bench as much as Brown wanted to get back to his Arabian horses, but she's on the job, and by all accounts as alert and committed as ever.

But what's a professional in a key job supposed to do when no matter how hard he or she tries, there is no way to focus on the job at hand for its remaining days, weeks or months? What is the ethical course of action then?

Simple: be honest and responsible, and quit. Explain to your superiors that you no longer can do the job, and will do more damage than good if you remain. Make yourself available for consultation and do everything possible to ease the transition, but step down so there's no mistaking the fact that you are no longer in charge. That's what a star baseball general manager did at the end of October, as Boston Red Sox GM Theo Epstein stunned everyone in the baseball universe by announcing that he was no longer able to commit himself emotionally and mentally to a demanding and stressful job under constant public and media scrutiny, and resigned…just as he was about to see his salary increase by almost 500%. Epstein's surprise exit put the Red Sox in a tough bind heading into a crucial off-season period of free-agent pursuit, trades, and contract negotiations, but he would have put the team in a far worse one if he had undertaken the daunting challenges of his job in a state of diminished commitment.

Doing a job ethically includes knowing when and how to quit. Apparently this was just one more aspect of his duties at FEMA that Michael Brown never mastered, and never understood until it was too late.