The U.S. Food and Drug Administration on Tuesday asked a U.S. appeals court to undo a lower court ruling that said such labels were unconstitutional, violating tobacco companies' free-speech rights.

Mark Stern, a lawyer from the U.S. Justice Department representing the FDA, said the labels showing, for example, a man smoking through a hole in his throat were necessary to show the true risks of smoking, including addiction.

"Adolescents notoriously underestimate their ability to resist addiction," he told the U.S. Court of Appeals for the District of Columbia Circuit.

"Do (these labels) accurately and realistically depict the message that this is really addictive? Yes, (they) do."

The Centers for Disease Control and Prevention estimates some 45 million U .S. adults smoke cigarettes, which are the leading cause of preventable deaths in the United States.

Congress passed a law in 2009 that gave the FDA broad powers to regulate the tobacco industry, including imposing the label regulation. The law requires color warning labels big enough to cover the top 50 percent of a cigarette pack's front and back panels, and the top 20 percent of print advertisements.

The FDA released nine new warnings in June 2011 to go into effect in September 2012, the first change in U.S. cigarette warning labels in 25 years. Cigarette packs already carry text warnings from the U.S. Surgeon General.

Reynolds American Inc's R.J. Reynolds unit, Lorillard Inc, Liggett Group LLC, Commonwealth Brands Inc, which is owned by Britain's Imperial Tobacco Group Plc , and Santa Fe Natural Tobacco Co Inc challenged the rule, arguing it would force them to engage in anti-smoking advocacy against their own legal products.

"You don't have to be Sherlock Holmes ... to figure out what the government is doing here: telling people, 'Quit smoking now,'" said Noel Francisco, a lawyer with Jones Day in Washington, D.C., who represents the tobacco companies.

He said the labels went beyond simple facts about smoking, instead trying to disgust or revolt people about cigarettes.

U.S. District Judge Richard Leon sided with the tobacco companies in a February ruling, saying the warning labels were too big and the government could use other tools to deter smoking, such as raising taxes or using factual information on the labels rather than gruesome images.

One of three appeals court judges who heard the case on Tuesday also appeared to question whether the government was going too far in trying to warn people about smoking.

"Could you have a text that says, 'Stop, if you buy this, you are a moron'?" asked Judge Janice Rogers Brown.

And Judge A. Raymond Randolph wondered if the government could also place warning labels on automobile doors with gruesome images of car accidents to warn people about the risks of speeding.

However, Randolph disagreed with the tobacco companies, saying there is no case that shows commercial disclosure should only provide information, not deter use of a product.

The judges will rule on the case later, but any decision is likely to be appealed further and could eventually reach the U.S. Supreme Court, especially as the tobacco law has led to divergent rulings in lower courts.

The U.S. Appeals Court for the 6th Circuit, based in Cincinnati, upheld the bulk of the FDA's new tobacco regulations last month, including the requirement for warning images on cigarette packs.

The case on Tuesday was R.J. Reynolds Tobacco Company et al v. FDA, U.S. Court of Appeals for the District of Columbia Circuit, No. 11-5332.

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