All good points . . .

However, I think that the issue of Brian Ross' sources might be a little more complicated than you present. I think it is possible, and perhaps even likely, that the sources themselves had been lied to. In other words, the sources themselves may not have fabricated the story but were (knowingly or not) passing along a falsehood. In this case, the source of the falsehood should be identified, but that source might not be known to Ross.

That's possible, but I don't think they would have published this story (and certainly shouldn't have) if at least one of their sources didn't have first-hand knowledge of the tests. One of the things I noted in the post from last week is that there is a report where Ross said -- "Former UN weapons inspectors have told ABC News they've been told the anthrax spores found in the letter to Senator Daschle are almost identical in appearance to those they recovered in Iraq in 1994" -- which lends support to your point.

But in other reports, they definitively stated that the bentonite was found and that multiple "highly placed" sources (a term inapplicable to "former UN weapons inspectors") told them that.

One other thing, just for the sake of accuracy. You dismiss the claim of the diagnostic value of the presence of bentonite in the anthrax spores by noting the widespread availability of bentonite. However, my reading of the reporting is that bentonite is supposedly diagnostic not because it is rare or available only in Iraq, but because its use in weaponizing antrhrax was unusual (and perhaps unique to Iraq).

Yes and no, but a fair enough criticism. Part of the sensationalistic tone of ABC's report came from their depiction of bentonite as "troubling chemical additive" -- as though it's something inherently dangerous and rare. It is NOT a "chemical additive" at all, and there is nothing "troubling" about it.

Though you're right that there's a distinction between (a) how common bentonite is and (b) its use in biological weapons, the fact that it's so commonplace means that it's absurd to think (and certainly to state definitively on a news program) that finding bentonite in anthrax points to Iraq, precisely because anyone could use it for that. As a WSJ article reported in October, 2001:

"The presence of bentonite could be a stronger indication that a state- sponsored weapons program such as Iraq's was involved in the development of the anthrax, said one US official, adding that if bentonite is confirmed, 'it raises it to a whole new level of sophistication.'" But "he noted that a technically proficient individual also could have learned about using bentonite as an additive in scientific literature. The US also has experimented with anthrax and bentonite, though the stocks were destroyed in the 1960s."

Before you run around with a lead story on ABC News fingering Iraq for the anthrax attacks, way more basis than the bentonite claim -- EVEN IF it were true that bentonite were found -- would be needed. Even a finding of bentonite was nowhere near compelling evidence that Saddam was behind those attacks, let alone a "smoking gun" -- the term used by Jennings to describe how it would be depicted.