A food industry watchdog group is threatening to take McDonald's to court over its practice of including toys with Happy Meals.
The Center for Science in the Public Interest announced Tuesday that it will file a lawsuit against McDonald's, calling the practice of marketing toys with junk food "illegal" under consumer protection laws in Massachusetts, Texas, the District of Columbia, New Jersey and California.
"Dangling a toy in front of a kid to try to get them into your restaurant is unfair and deceptive, because it's targeted at kids who are what? Four years old? Six years old? Who don't even understand the concept of advertising," Michael Jacobson, executive director of CSPI, said in an interview with ABC News' Yunji de Nies.
"It's not just a meal. It's the technique you're using to get kids to buy a meal," he said.
In a media statement e-mailed to ABCNews.com, William Whitman, vice president of communications at McDonald's USA, said, "We couldn't disagree more with the misrepresentation of our food and marketing practices made by the Center for Science in the Public Interest. Since 2006, we have been a part of the Council for Better Business Bureau's voluntary initiative to address the importance of children's well-being.
"In the U.S., McDonald's primarily advertises the four-piece Chicken McNuggets Happy Meal, which includes Apple Dippers, low-fat caramel dip and 1 percent low-fat white milk," Whitman said in the statement. "Happy Meals are right-sized for kids, a concept that has not changed since its introduction in 1979."
Pediatric nutritional experts said they certainly recognized the food marketing power of toys adapted from movie characters and TV. But not all agree with the CSPI's campaign against toys in Happy Meals.
"This is marketing pure and simple, and routinely this marketing is used to encourage kids to eat foods that propel them toward diseases that we don't want them to get -- such as diabetes," said Dr. David Katz, director of the Yale University Prevention Research Center.
In a press release, CSPI pointed to a 2008 study by the Federal Trade Commission, which found that food companies spend more than $350 million on toy giveaways each year.
Katz said there was no question that toys were an effective way to steer children to Happy Meals.
"Their actions that are on public display convince me," said Katz. "The entities in the food industry that are pedaling the most questionable fare have the deepest pockets.
"Where there is debate is on how to regulate the marketing of what we'd called junk food for children," said Katz.
Katz hopes the attention from the threatened lawsuit against the fast-food chain may bring the matter to the attention of parents.
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"I often think that CSPI goes to relatively extreme positions, but quite frankly, I'm glad they do because it draws attention," he said.
But others who treat childhood obesity said the issue of what children should eat is a decision for parents, not the courts.
"I am surprised that this is his [Jacobson's] focus because now especially, today's Happy Meals are not Yesterday's Happy Meals," said Keith Thomas Ayoob, an associate professor and director of the Nutrition Clinic at Rose R. Kennedy Center at the Albert Einstein College of Medicine in New York City.
In recent years, McDonald's has changed the choices for Happy Meals to allow customers to swap out soda for low-fat milk, or fries for apples.
"You can get a simple plain hamburger with low-fat milk and fresh apple slices, and that's actually a meal that fits in with dietary guidelines. That's a reasonable choice," said Ayoob.
Ultimately, Ayoob said it "becomes a parenting issue of who is in charge. My parents never had any difficulty telling me no."
In a CSPI letter to McDonald's obtained by ABC News, CSPI acknowledged that McDonald's pledged to "advertise only Happy Meals that meet McDonald's nutrition standards for children" through the Children's Food and Beverage Advertising Initiative of the Council of Better Business Bureaus.
However, the letter also includes the results from a small CSPI research study of 44 McDonald's outlets in which CSPI found "in response to a request for a hamburger Happy Meal, the McDonald's employee, without asking customers which side dish they wanted, provided fries 93 percent of the time."
When asked why CSPI singled out McDonald's from any other restaurant that appeals to children with coloring books or playgrounds, Jacobson said the size of the marketing reach was what mattered
"McDonald's is so much bigger than any other restaurant, so much more aggressive in marketing its products to kids, and the toy is the centerpiece of its marketing," Jacobson told ABC News. "That's why every popular film that comes out, McDonald's is there to take advantage of the characters to entice kids into their restaurants. I don't know of any other restaurant company that does something of the same magnitude that McDonald's is [doing]."