The article looked into the activities of companies behind the finances of the Presidential campaigns for George W. Bush and his father. Barrick Gold Mining, which backed Bush Senior's campaign, claims libel because the Observer quoted an Amnesty International report which alleged that 50 miners might have been buried alive in Tanzania by a company now owned by Barrick.
The mining company is also demanding that the investigative journalist Greg Palast should be forced to remove his offending article from his own US web site, gregpalast.com. Palast says that Barrick wants the Observer "to state what we know to be untrue: that independent investigation found the charges completely baseless."
As Palast observes, UK defamation law does not allow a defence of repetition. US law, backed by the Constitution's right to freedom of speech, is more liberal in this field.