The ratings agency is being sued for fraud by the US Department of Justice in relation to its ratings on mortgage-related securities in the run-up to the credit crunch. 

But in a filing of documents yesterday, S&P connected the lawsuit as an attack on free speech. The filing says, according to the Financial Times: 'Such free speech is protected under the First Amendment to the United States Constitution and the retaliation, causing and embodied in the commencement of this impermissibly selective, punitive and meritless litigation, is unconstitutional.' S&P's lawyer, Floyd Abrams, has claimed that the government investigation on S&P 'intensified' after the ratings agency downgraded the US from a triple A rating.

Optimistic

The government claim is that S&P gave unduly optimistic ratings on mortgage-related securities as a way of winning business. S&P lawyers have been granted rights to see emails and other documents from the Department of Justice and the Treasury which could prove its case that the litigation was limited to the downgrade.