It is an axiom of the new digital media age that high-profile political columnists should generally avoid copying other people's words without attribution. Nobody wants to have the p-word hung around their necks.

It is a further axiom of the age that if a columnist is to borrow a paragraph unattributed, then at least they should ensure it doesn't belong to Josh Marshall. The man behind Talking Points Memo is one of the sharpest, most deadly bloggers around.

Maureen Dowd, the New York Times columnist, has cause to ponder both these axioms today after she found herself sucked into a spat over plagiarism. In her column yesterday she launched an attack on Dick Cheney for the former US vice-president's stance on torture, but in the process merely seems to have inflicted ethical torture upon herself.

In the article, Dowd wrote: "More and more the timeline is raising the question of why, if the torture was to prevent terrorist attacks, it seemed to happen mainly during the period when the Bush crowd was looking for what was essentially political information to justify the invasion of Iraq."

The paragraph is word-for-word identical to a section of a blogpost by Marshall last week, the only difference being that in place of "the Bush crowd was" he had written "we were". That's the kind of thing that doesn't slip by unnoticed.

Marshall has an enviable track record of investigative reporting.

Through the New York-based Talking Points Memo, or TPM to its many fans, he broke the story of the Bush administration's politicised sacking of federal lawyers in 2007; his Muckraker blog is a scourge of corrupt politicians.

Dowd's self-defence, posted through rival liberal blog the Huffington Post, is that she didn't read TPM at all last week. She had been given the idea of the paragraph talking to a friend whom she assumed had been speaking spontaneously.

"Clearly, my friend must have read Josh Marshall without mentioning that to me."

The mistake, corrected by the paper, is paradoxical for Dowd who in 1987 broke a major political plagiarism story. She revealed that then Delaware senator Joe Biden had copied speeches made by Neil Kinnock, then leader of the Labour party in the UK.

Her story placed Biden in such bad odour that he pulled out of the 1988 presidential race.

Two decades later Biden is vice-president - Cheney's replacement.

The plagiarism scandalette is a blip on an otherwise soaring career. Dowd has been described as the most powerful woman columnist in America, and she is certainly among the best connected and glamorous.

She is the author of two bestsellers – Bushworld and her take on the gender wars Are Men Necessary? - and won a Pulitzer prize for distinguished commentary in 1999.