Politicians, like regular human beings, do bad things. Some of them have affairs, sexually harass women, lie, do drugs, drive drunk and so on.

Unlike you and me, however, politicians do things like sell their votes, use public policy to shake down companies for contributions or jobs, regulate industries and then sell their insider knowledge to the biggest players in those industries, and so on.

The first class of misdeeds are personal failings. The second class is public corruption.

Public corruption is obviously the concern of the public. Congressmen, mayors and top-level officials caught up in public corruption should be driven from office and maybe prosecuted.

As we consider the case of freshman Rep. Trey Radel, R-Fla., arrested last month for cocaine possession, we should recall that personal failings are often not the concern of the public. But in some circumstances, they are:

1) Did the politician abuse public power to carry out, perpetuate or cover up this failing?

Bob Filner sexually harassed subordinates. Bill Clinton and John Ensign both used their jobs to try to get jobs for people involved in their affairs. Clinton used the power of government to punish folks looking into his affair. This turns a private failing into a case of public corruption.

There's no evidence Radel did anything like that.

2) Did the politician repeatedly and publicly lie to cover up the failing?

The Lewinksy affair proved (if we didn't know) that Bill Clinton had zero problem lying blatantly and repeatedly in public and zero problem intentionally misleading under oath. This reflects on his unfitness for public trust. The same goes for Anthony Weiner.

I feel like a single lie in the heat of the moment is one thing. Repeatedly and deliberately lying shows a deep dishonesty.

I don't think Radel ever lied to cover up his interest in cocaine or his drinking problem.

3) Does the personal failing reflect an inability to carry out the duties of office?

This is where we get closest to Radel. If Radel's alcohol use or drug use gets in the way of his doing his job, that's something for voters or the GOP leadership to take into consideration.

Is he an addict who has trouble functioning? Does doing coke get in the way of being a member of Congress? Sure. But so does having a baby. So does trying to sell your house. So does having a sick parent or spouse. But we tolerate our politicians having personal distractions — to a point.

Another question: Is a politician opening himself up to blackmail through his personal failings?

Maybe Radel is. And if he were an executive — a governor or a mayor, for instance — these concerns would be much greater. But until you show me Trey Radel is really unable to function, I don't see any reason for the public to press him to resign.

(That said, his wife has every right to have to a far lighter trigger finger on whether Radel needs to leave D.C.)