Some of the largest U.S. tobacco companies, including R.J. Reynolds Tobacco and Lorillard Tobacco, had questioned the labels' constitutionality, saying the warnings don't simply convey facts to inform people's decision on smoking but instead force cigarette companies to display government antismoking advocacy more prominently than their own branding.
The companies also said changing cigarette packaging would cost millions of dollars.
The Food and Drug Administration has said that the public interest in conveying the dangers of smoking outweighs the companies' free-speech rights.
In his ruling Wednesday, Leon wrote that the graphic images "were neither designed to protect the consumer from confusion or deception, nor to increase consumer awareness of smoking risks; rather, they were crafted to evoke a strong emotional response calculated to provoke the viewer to quit or never start smoking."
The judge also pointed out alternatives for the federal government to curb tobacco use, such as increasing antismoking ads, raising tobacco taxes, reducing the size and changing the content of the labels, and improving efforts to reduce youth access to tobacco products.
The FDA and the Justice Department declined to comment Wednesday.
Tobacco companies increasingly rely on their packaging to build brand loyalty and grab consumers. It's one of few advertising levers left to them after the government curbed their presence in magazines and on billboards and TV.