Yesterday, in conjunction with a forum they hosted on media bias, Rep. John Conyers (D-MI) and other House Judiciary Committee Democrats released a study by the nonpartisan Congressional Research Service examining coverage of key news stories on 13 cable news programs on CNN, MSNBC, and Fox News Channel in the three days after each story broke. The study shows that events such as the release of the Downing Street Memo, a secret British intelligence memo suggesting that the Bush administration manipulated intelligence to support its case for war in Iraq, and the revelation of Jeff Gannon's true identity received little or no coverage, while events such as the Scott Peterson trial and the beginning of the Michael Jackson trial received substantial coverage.

For example:

• The Downing Street Memo received no coverage on the 13 cable shows in the three days after the British news media reported on it.
• The revelation that Jeff Gannon, a partisan operative, had attended dozens of official White House press briefings using an assumed name also received no coverage in the three-day period after it occurred.

On the other hand:

• The filing of formal charges against Michael Jackson received coverage by 10 of the 13 shows on the first day alone, with four shows leading with the story.
• The Scott Peterson verdict received coverage on five shows the first day and eight the second, with five shows leading with the story.

Media Matters for America on coverage of the Downing Street Memo:

Downing Street Memo update

Media finally begins to notice British intelligence memo

Readers complain, but Wash. Post ombudsman mum on lack of coverage of U.K.-Iraq memo

What is media coverage of Iraq war good for? Absolutely nothing