It's a concept so basic that it is taught to - and understood by - small children: If you suspect or come across wrongdoing, call the police.
Then there's O.J. Simpson.
Since the 1994 murder of ex-wife Nicole Brown Simpson and her friend Ron Goldman, the former NFL star has navigated his path through public life into little more than a train wreck, without displaying one iota of contrition concerning the double slaying.
Simpson's latest misstep came Sunday, when Las Vegas police arrested him on felony charges stemming from an alleged armed robbery. Simpson says he was trying to get back personal sports memorabilia that was stolen years before.
Certainly if some of your prized belongings had been stolen, your first reaction would be to call officers who are trained to find and return stolen goods to their owners - legally.
Instead, Simpson is accused of barging into a hotel room with armed cohorts and demanding the memorabilia from a collector.
Here is Simpson's attorney, Yale Galanter: "You can't rob something that is yours. O.J. said, 'You've got stolen property. Either you return it or I call the police.' "
But did he say that? According to Simpson himself, he apparently had no intention of calling authorities.
"The police, since my trouble, have not worked out for me," he said. Whenever he has called police in the past, Simpson added, "It just becomes a story about O.J."
And that's a story, frankly, that we're sick of hearing.
One of Simpson's friends, Walter Alexander, told Good Morning America on Tuesday that this whole incident sounds like a setup. Regardless of whether that's true, it shouldn't even have happened in the first place. It just puts on display, yet again, Simpson's chronic inability to discern right from wrong.