U.S. District Judge Samuel Conti in San Francisco dismissed some but not all of the lawsuit by consumers of Clorox's Fresh Step letter brand. The lawsuit said scientific studies showed Fresh Step wasn't preferred by cats over other litters or more effective at cutting down odors.

A lawyer for Clorox, Kenneth Lee, declined comment. Lawyers for the plaintiffs did not respond to requests for comment.

The decision came amid a series of legal headaches that have dogged Clorox over its advertising for Fresh Step, a popular brand of cat litter which has been on the market since 1984.

The company faced two separate lawsuits in New York by rival Church & Dwight Co Inc, the maker of litter Arm & Hammer Super Scoop, claiming Clorox's commercials were misleading.

One set of ads depicted cats choosing a box of Fresh Step over one with Super Scoop and stated they're "smart enough to choose the litter with less odors." Another set said Clorox made "scoopable litter with carbon, which is more effective at absorbing odors than baking soda."

Church & Dwight, whose litter uses baking soda, went so far as to commission a laboratory to study its litter's odors compared to Clorox's and swayed a judge in January to blocked one set of Clorox commercials.

The companies have since settled, but after the judge's January order, consumers sued.

In his decision Friday, Conti dismissed the plaintiffs' claims to the extent they were based on Clorox's statements that cats "like" or "are smart enough to choose Fresh Step."

"But he said the lawsuit could proceed "to the extent that it is predicated on Clorox's representations that Fresh Step is better at eliminating odor than other baking soda-based cat litters."

The case is In re Clorox Consumer Litigation, U.S. District Court for the Northern District of California, 12-cv-00280

(Reporting By Nate Raymond in New York)

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