NEW YORK, April 20 (Reuters Legal) - Rival wine sellers targeting overworked mothers are fighting over use of the word "Mommy" on their wine labels, according to a lawsuit filed in San Francisco federal court.

In the suit, filed on Monday, California-based winery Clos Lachance Wines asked the court to declare that its "Mommyjuice" does not violate the trademark of "Mommy's Time Out," which is marketed by a New Jersey distributor.

"Mommy is a generic word that they don't have a monopoly on," said KC Branch, an attorney who represents Clos Lachance.

The owner of "Mommy's Time Out" declined to comment on the lawsuit.

To succeed in a trademark violation case, a brand owner must show it is likely that a rival's mark will create confusion in the minds of consumers.

The front label of Mommyjuice features a drawing of a woman juggling a house, teddy bear and computer. The back label advises moms to "tuck your kids into bed, sit down and have a glass of Mommyjuice. Because you deserve it." The wine is available in a white Chardonnay and a red mixed blend.

The front label of "Mommy's Time Out," an Italian wine sold in red and white, shows an empty a chair facing a corner. A wine bottle and glass sit on a table next to the chair.

Trademark conflicts between winemakers are relatively common, said Richard Mendelson, a California vintner who teaches a course on wine law at Boalt Hall School of Law in Berkeley.

"For a wine coming out to market, it's hard to find a name that's not in use," he said.

Mendelson also noted that wines with "fanciful" names have proliferated as marketers try to reach new categories of customers. In recent years, vinters have launched wines like "Fat bastard," "Cleavage Creek" and a red wine featuring a rooster called "Big Red Pecker."

The case is: Clos LaChance Wines v. Selective Wine Estates, U.S. District Court for the Northern District of California, No. 11-1848.

(Reporting by Jeff Roberts)