The biggest story to emerge from the Republican National Convention was the media's effort to destroy Gov. Sarah Palin. Members of the Fourth Estate behaved more like a Democratic fifth column this week than they did like honest reporters. Palin's stunningly effective speech Wednesday night showed they will not easily take her down -- but their malicious attacks on Gov. Palin's family prove that they will stop at nothing to achieve their aim. Since when is the private life of a 17-year-old fair game in a political campaign? Apparently only when that 17-year-old's mom is a Republican candidate.

Make no mistake -- the press outed Bristol Palin's pregnancy. Reporters descended on Alaska following vile and false accusations on Internet blogs that Gov. Palin faked her own pregnancy and that her daughter was actually baby Trig's mother. These lies weren't only spread by left-wing fanatics but by journalists like Andrew Sullivan, whose blog appears on Atlantic.com, the online version of what was once one of the most respected magazines in the country. As the rumors got uglier, the McCain campaign decided they had no choice but to reveal to the world intimate details about Gov. Palin's daughter. And the media stood by their decision to muckrake by arguing for the public's right to know.

If you don't think this reflects media bias, contrast this insatiable prying into Bristol Palin's life with the press's lack of curiosity about the behavior of another 17-year-old -- one whose story would seem to have more relevance to this year's presidential election.

In his memoir "Dreams from My Father," Barack Obama describes his troubled teenaged years. "Pot had helped, and booze, maybe a little blow when you could afford it. Not smack though," he recalls, though he admits he came close to trying heroin at the urging of a friend who shot up in front of him. He was deterred by the image "of an air bubble, shiny and round like a pearl, rolling quietly through my vein and stopping my heart," he says. "Junkie. Pothead. That's where I'd been headed: the final, fatal role of the young would-be black man."

Obama's drug use went on for at least a few years, though he is noticeably vague in describing exactly when it began, how extensive it was, or when it ended. At least one of his friends was arrested for drug possession; another had a mental breakdown after one too many acid trips. But Obama has been reticent to reveal the extent of his illegal activities -- and the media haven't cared enough to pursue the question.

Past drug use by presidential candidates was considered a legitimate subject of inquiry for Bill Clinton (who, famously, "didn't inhale") and George W. Bush. News organizations devoted considerable investigative resources in 2000 to track down unsubstantiated rumors about Bush's alleged cocaine use -- and printed the accusation, even when there was no credible evidence that it was true. Yet those same news organizations treat Obama's admitted -- and apparently heavy -- youthful drug use as if it were off-limits.

What a candidate did as a young man -- even if it was illegal -- should not necessarily disqualify him from becoming president. But shouldn't we want to know a bit more than he's volunteered to date before we make a final judgment? Did Obama ever sell drugs to anyone? When was the last time he used cocaine? What other illegal drugs has he used? As an adult, has he been present when others were using illicit drugs?

Why is it reporters who were willing to pursue Bristol Palin, who isn't on the ballot, somehow think it is unseemly to ask Sen. Obama tough questions about his drug use? Oh, that was a long time ago, they'll argue. But a 1986 arrest for driving while impaired by Gov. Palin's husband -- not the candidate -- is somehow worthy of extensive front-page coverage?

The double standard is shocking -- but perhaps not to Sen. Obama. In his memoir, he gives the most telling explanation of how he has gotten away with avoiding discussions of his drug use. It was the same technique he used on his mother when she confronted him in his senior year of high school: "I had given her a reassuring smile and patted her hand and told her not to worry, I wouldn't do anything stupid. It was usually an effective tactic, another of those tricks I had learned: People were satisfied so long as you were courteous and smiled and made no sudden moves."

With two months left to Election Day, it will be a test of the media's integrity to see if they devote as much time delving into Sen. Obama's drug use as they did into Bristol Palin's sex life.