On January 7, 2015, the U.S. District Court for the Central District of California held that California's ban on the sale in California of foie gras--a delicacy made from fattened and force-fed duck liver--was preempted by federal law, namely the Poultry Products Inspection Act (PPIA), 21 U.S.C. §§ 451-470. The case is Associations Des Eleveurs De Canards et D'Oies Du Quebec, et al., v. Kamala Harris, Attorney General of California. This is an example of the preemptive effect of federal legislation, which will often trump conflicting state law, especially in business matters.
The plaintiffs, a group of Canadian farmers, alleged that this ban has caused them to lose millions of dollars in sales in California, and the court held that they had standing to bring this lawsuit. The District Court then reviewed the California statute (enacted in 2012) and the provisions of the PPIA, and determined that the California law conflicts with and is preempted by the federal law, which regulates the distribution and sale of poultry products in interstate commerce.
Some of the issues in this case have already been reviewed by the Ninth Circuit, which held in 2013 that the California Attorney General was not entitled to Eleventh Amendment immunity (see 729 F. 3d 937), and it is likely that another appeal will be made to the Ninth Circuit. The Ninth Circuit has recently upheld several state laws against such challenges.