BBC:

The firms argue the plan violates their constitutional right to free speech, as it requires firms to promote the government's anti-smoking message.
The FDA has not commented on the lawsuit.
The new warnings will be required on cigarette packs from September 2012.
'Depressed, afraid'
RJ Reynolds Tobacco, Lorillard Tobacco, Commonwealth Brands, Liggett Group and Santa Fe Natural Tobacco said they filed their suit against the FDA late on Tuesday in an effort to delay enforcement of the new law.
RJ Reynolds brands include Camel and Winston, while Lorillard brands include Newport and True.