CHICAGO — A battle between the makers of the two largest brands of artificial sweetener heats up Monday in a Philadelphia courthouse. That's when lawyers for the little yellow packet, Splenda, will try to convince jurors that its slogan, "Made from Sugar, So It Tastes Like Sugar" is not misleading, as charged by the Chicago-based maker of the little blue packet, Equal.

Unless settled, the trial foreshadows an even larger battle later this year between the nation's sugar industry and McNeil Nutritionals LLC, the Johnson & Johnson subsidiary that unleashed a marketing juggernaut on behalf of Splenda after unveiling the slogan in 2001.

Both Chicago-based Merisant Worldwide Inc. and the Sugar Association, the marketing arm of the American sugar industry, charge that Splenda's marketing campaign has deceived the public into believing that the yellow packet is made from, or contains, sugar. The sugar industry and Merisant claim they have lost millions of dollars in sales as a result of Splenda's spectacular success. First introduced in 2001, sales have risen from $34 million to $212 million in 2006. One key advantage it offers is that it performs equally well when heated in baking or cooking, something that Equal or Sweet 'n' Low, the third-largest-selling artificial sweetener, are unable to claim. Previously, only sugar could make that claim. Merisant is seeking damages totaling $176.1 million.

During the five years that Splenda's sales have been soaring, Equal's sales have fallen $30 million, while the sales of sugar have fallen $85 million. Splenda now holds 59 percent of the U.S. artificial sweetener market, while Equal holds 13.7 percent. Privately held Sweet 'n' Low has 13.5 percent of the market. In 2001, it was the reverse: Equal held 33.8 percent of the market, compared to Splenda's 13.9 percent.

Paul Block, chairman and chief executive of privately held Merisant, which has worldwide sales of more than $300 million, believes Equal would not have been hurt so severely had Splenda been prevented from using the slogan.

"Things would be very different if we were allowed to compete on an even playing field in a way where consumers got accurate information to base their purchases upon," he said. "When you can say things that are false and misleading which are very compelling to the consumer, it is a tremendous advantage."

Philadelphia Federal District Court Judge Gene Pratter sees the dispute as focused on language.

"The phrase 'made from sugar' may sound simple enough, and may eventually prove not to be misleading to consumers, but it has spawned (an) epic battle among the parties over proper diction and syntax," she wrote in an opinion earlier this month when she refused to dismiss the Merisant lawsuit.

"For example, McNeil claims that 'made from sugar' clearly excludes the interpretation that Splenda is sugar, or that Splenda is made with sugar. Made with sugar would mean that sugar is an ingredient listed on the package. ... McNeil asks the question, how could a consumer interpret a product that is 'made from sugar' and 'tastes like sugar' as actually being sugar?"

Jonathan Cole, Merisant general counsel, said: "Merisant will expose the truth about Johnson & Johnson's carefully orchestrated campaign to mislead consumers and confuse the public."

Johnson & Johnson's McNeil defends its slogan by saying that Splenda is "made from pure cane sugar," which is converted through a three-step chemical process into an artificial sweetener.

The company said it has not changed its marketing since the day the product was introduced in 2001.

Block said Merisant is willing to duke it out in the grocery aisles.

"We just want it to be on a level playing field," he said.