Oprah is one of those celebrities who has power that is a little unsettling.

A recommendation or interview can propel a book's sales into the stratosphere, if something becomes one of Oprah's favourite things it flies off the shelves and she can seemingly do no wrong, even though the Texan cattle producers tend to disagree.

Now Oprah has turned her ire on people who text or call while driving. Several states have laws governing mobile use while in the car and now the queen of daytime television has thrown her weight behind the campaign.

She devoted her program to "National No Phone Day," a campaign with rallies in Atlanta, Boston, Detroit, Los Angeles and Washington, D.C today across the US demanding restrictions on in-car calls. She's also sponsoring an advert against calling in cars and is calling on viewers to take the no-phone pledge.

The cause is a good one. According to a National Highway Traffic Safety Administration study 6,000 people were killed by distracted drivers in 2008, and half a million people injured. But the question remains as to whether it will work.

Here in California that job is done - only the police can use a mobile phone in their hand while driving, while everyone else now has to use a wireless headset. That's the law but people aren't obeying it as far as we can see, if the idiot who nearly sideswiped Sleuth on Market Street today was anything to go by.