Editor's note: David Frum is a contributing editor at Newsweek and The Daily Beast and a CNN contributor. He is the author of seven books, including a new novel, "Patriots."
(CNN) -- Of all the speeches at the Democratic convention in Charlotte, North Carolina, few offended conservative listeners more than the speech by Sandra Fluke.
There are plenty of good reasons to be annoyed. From the conservative point of view, Fluke is on the wrong side of a battle over religious freedom. Back in March, she testified in favor of a proposed Obama administration rule that would require Catholic institutions, like her own Georgetown University law school, to reject the teaching of their church and cover contraception in their university health plans -- plans not funded by taxpayers, by the way, but by tuition and other university revenues.
Now here Fluke was again, on the national stage, warning that a vote for the Republican ticket in 2012 was a vote for "an America in which you have a new vice president who co-sponsored a bill that would allow pregnant women to die preventable deaths in our emergency rooms. An America in which states humiliate women by forcing us to endure invasive ultrasounds we don't want and our doctors say we don't need.
"An America in which access to birth control is controlled by people who will never use it; in which politicians redefine rape so survivors are victimized all over again; in which someone decides which domestic violence victims deserve help, and which don't."
Shortly before Fluke spoke, conservative commentator Ann Coulter had tweeted: "Bill Clinton just impregnated Sandra Fluke backstage."
That was nothing compared with the outpouring of fury during and after the speech.
Stephen Kruiser, who hosts on the conservative Internet video site PJTV and appears on Fox's "Red Eye," tweeted mid-speech: "Tricky camera work to keep TV audience from seeing (David) Axelrod's hand up Fluke's a**."
The next day, National Review columnist and sometime Rush Limbaugh guest host Mark Steyn scoffed: "Sandra Fluke has been blessed with a quarter-million dollars of elite education ... and she has concluded that the most urgent need facing the Brokest Nation in History is for someone else to pay for the contraception of 30-year-old children."
James Taranto, columnist for the online edition of The Wall Street Journal, was nearly equally scathing. "Seriously, the party of Andrew Jackson and Franklin D. Roosevelt and Harry S. Truman chose to showcase someone whose claim to fame is that she demands that somebody else pay for her birth control."
Within 48 hours, the attack had jumped from the conservative media sphere to electoral politics. Campaigning in Addison, Illinois, Republican congressional candidate Joe Walsh erupted: "Think about this, a 31-, 32-year-old law student who has been a student for life, who gets up there in front of a national audience and tells the American people, 'I want America to pay for my contraceptives.' You're kidding me. Go get a job. Go get a job, Sandra Fluke."
There's never any shortage of vitriol in political commentary, but usually it's reserved for the headliners. Yet Fluke provoked more sputtering in five minutes than former President Bill Clinton did in a speech 10 times as long.
The answer takes us to the events that put Fluke on the stage in Charlotte in the first place: Rush Limbaugh's brutal, sexualized attack on her congressional testimony.
On the day after Fluke spoke, Limbaugh demanded: "What does it say about the college co-ed Sandra Fluke, who goes before a congressional committee and essentially says that she must be paid to have sex, what does that make her? It makes her a slut, right? It makes her a prostitute. She wants to be paid to have sex. She's having so much sex she can't afford the contraception. She wants you and me and the taxpayers to pay her to have sex. What does that make us? We're the pimps."
Limbaugh returned to the subject again and again, escalating his abuse over three consecutive days. "So Miss Fluke, and the rest of you feminazis, here's the deal. If we are going to pay for your contraceptives, and thus pay for you to have sex, we want something for it. We want you to post the videos online so we can all watch."
After three days of this, advertisers began to drop his show -- and Limbaugh was constrained to issue a grudging apology on his website.
"For over 20 years, I have illustrated the absurd with absurdity, three hours a day, five days a week. In this instance, I chose the wrong words in my analogy of the situation. I did not mean a personal attack on Ms. Fluke.
"I think it is absolutely absurd that during these very serious political times, we are discussing personal sexual recreational activities before members of Congress. I personally do not agree that American citizens should pay for these social activities. What happened to personal responsibility and accountability? Where do we draw the line? If this is accepted as the norm, what will follow? Will we be debating if taxpayers should pay for new sneakers for all students that are interested in running to keep fit? In my monologue, I posited that it is not our business whatsoever to know what is going on in anyone's bedroom nor do I think it is a topic that should reach a presidential level.
"My choice of words was not the best, and in the attempt to be humorous, I created a national stir. I sincerely apologize to Ms. Fluke for the insulting word choices."
In this grudging half-apology, half-justification, Limbaugh misstated the facts of the case. Taxpayer money was never at issue between Fluke and Georgetown. When Fluke and her fellow students paid tuition to Georgetown, they got health coverage as part of the deal.
At issue in Fluke's congressional hearing were principles of religious freedom -- and the disposition of student health dollars -- but not taxpayer money.
Limbaugh's misstatement had the benefit of permitting him a change of subject -- and a way out of a damaging controversy. And it allowed his friends and supporters to pronounce the matter closed.
Yet somehow it didn't close: not for Fluke, and not for Limbaugh either.
Other male commentators have used belittling, misogynistic language against other women in the public eye. Both Republican and Democratic women have found themselves on the receiving end of condescension and epithets.
But Limbaugh did something different with Fluke: Aggressively and deliberately, over a long span of days, because his own commercial interests require shock and controversy, Limbaugh had promoted Fluke into a totem and martyr. When Democrats later claimed that Republicans "waged war on women," Limbaugh's tirade became Exhibit A -- at least until Rep. Todd Akin's "legitimate rape" comment demoted it to second place.
At the time of the tirade, a number of Republican politicians spoke out against Limbaugh. U.S. Sen. Scott Brown called Limbaugh's comments "reprehensible" and former Senate candidate Carly Fiorina condemned them as "insulting."
Yet as time has passed, the regrets faded. An idea was born and grew that somehow Fluke must have provoked what was said of her, must indeed have deserved it.
Erick Erickson of CNN and Red State.com expressed this "she asked for it" view pungently in a March blog post: "Of course Rush Limbaugh was being insulting. He was using it as a tool to highlight just how absurd the Democrats' position is on this. It's what he does and does quite well. And in the process he's exposing a lot of media bias on the issue as people rush out (no pun intended) to make Sandra Fluke a victim of his insults and dance around precisely what is really insulting ? her testimony before congress that American taxpayers should subsidize the sexual habits of Georgetown Law School students because, God forbid, they should stop having sex if they cannot afford the pills themselves."
That mood, an undercurrent until recently, gushed into full view on the night of Fluke's convention speech. If the words "slut" and "prostitute" are not to be used, she must nonetheless be the thing indicated by those not-to-be-used words: a woman whose sexuality is for sale. Because if she's not -- if she's merely a concerned citizen who expressed in a public forum a diverging view of the appropriate relationship between church and state -- then what does that make Limbaugh?
And what does it make those who rallied to defend Limbaugh? Something pretty ugly, right? Which is why it remains today so urgently necessary for so many people to demean and defame this woman.
The correct reply to Fluke is that she is a person intolerant of the religious liberty of the Catholic Church. The Catholic Church does good works on a vast national scale -- caring for the sick, teaching children, supporting the homeless -- all to uphold its compassionate doctrines in a harsh world. Once government starts imposing its rules on a church, then it crushes the spirit that leads the church to do its good on the world.
You can say all that without hurling accusations of nymphomania, freeloading and sexual exhibitionism. In fact, omitting such vile insults makes the rebuttal more convincing, not less. But that's not how Rush Limbaugh does it, and he has taught a generation of conservative shock-mongers to do the same or worse.
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The opinions in this commentary are solely those of David Frum.