Peter Beinart says in The New York Times Book Review,

It's remarkable to me how many people still mention the fact that [the anti-abortion Pennsylvania governor] Bob Casey was denied the right to speak at the 1992 Democratic convention. That was an illiberal thing the party did.

Atrios, among others, denounces this as an urban legend.

Casey wasn't denied the opportunity to speak because he was anti-choice, he was denied the opportunity to speak because he refused to endorse the Clinton/Gore ticket.

Over at The Washington Monthly, Kevin Drum does a Nexis search of articles on the subject and concludes,

So it seems to me that the real reason Casey was prevented from speaking was because....he wanted to give a pro-life speech.

But a commenter named Jane says he's missing the point:

... The right-wing meme isn't that Casey was prevented from speaking because he wanted to give a pro-life speech, it's that Casey was prevented from speaking *because he was pro-life.* Veerrry different....

Repeat-- the GOPers keep saying Casey was denied a speaking slot because of his beliefs, not because of what he intended to say.

She's absolutely right. And it's a vital distinction. Now and for the foreseeable future, no one's going to get up at a Republican convention and make a speech the central thrust of which is opposition to the Iraq war, or support for higher taxes, or advocacy of gay marriage or abortion rights. Everyone knows that. Thus, in order for the Casey story to retain potency, it must appear that the party kept him off the stage because of his beliefs, not because the point of his speech was to rebuke to the presidential nominee on a key issue.

But that's precisely what a lot of people believe happened. And this is more than a right-wing meme now -- it's conventional wisdom.

Here's Zell Miller last summer on Meet the Press:

… the Republican Party has become the party where diversity is accepted. You know, they talked about diversity at the Democratic convention. There was no diversity in ideology whatsoever. Can you remember when they wouldn't even let Bob Casey, a pro-life Democrat, Governor of Pennsylvania -- wouldn't even let him speak at the convention in '92? They have completely pushed out any moderate to conservative Democrat. It's no longer the party of the big tent that it once was.

Here's Nat Hentoff (an anti-abortion zealot, as you know if you've read him regularly) eulogizing Casey in 2000 in The Village Voice:

Casey was not asked to speak. In fact, he and his Pennsylvania delegation were exiled to the farthest reaches of Madison Square Garden--because Casey was pro-life.

Here's the Catholic magazine Crisis:

Ultimately, Casey's opposition to abortion made him a pariah among the most radical Democrats. He was banned from speaking at the 1992 Democratic National Convention in New York.

Here's Jonathan E. Kaplan writing last summer in The Hill:

In 1992, Democrats did not allow Pennsylvania Gov. Bob Casey to speak because he was pro-life, even though he was a longtime liberal Democrat.

Here's a 2004 editorial in the St. Petersburg Times:

No one expected to find an antiabortion Democrat on the list of speakers [at the 2004 convention]. It simply isn't allowed. Feminists would object, just as they did at the party's 1992 convention, when Robert Casey, then governor of Pennsylvania and a genuine New Deal liberal, was denied a speaking role because of his opposition to abortion.

That's why I thank Digby for digging up this 1996 New Republic article by Michael Crowley on the Casey brouhaha. In addition to the other evidence Crowley marshals, he notes this:

...a slew of pro-life Democrats, including Chicago Mayor Richard M. Daley Jr., Senators John Breaux and Howell Heflin, and five governors, did address the delegates in 1992.

That's it. That's the smoking gun. How many anti-abortion Democrats got to speak at that convention? At least eight. Not primarily on abortion -- but they did get to speak.