The California Restaurant Assn. sued the City of Los Angeles, seeking to overturn an ordinance that requires restaurants, bars and liquor stores to post warnings about the danger of alcoholic beverages to pregnant women. The Los Angeles Superior Court suit claims that the 2-month-old ordinance is unconstitutional because the city has no legal authority to regulate the sale of alcoholic beverages. That regulatory authority belongs to the state, the 2,700-member association claims. Under the city ordinance, an estimated 7,200 businesses that sell liquor must post signs warning their customers that “drinking wine, beer and other alcoholic beverages during pregnancy can cause birth defects.” A spokeswoman for the association said it is difficult for restaurant owners to comply with a growing number of local ordinances governing the sale of alcoholic beverages.