However, the ruling did not strike down California Statute 32390, which declares all magazines greater than ten rounds to be a public nusience and are to be confiscated by authorities whenever encountered.
So you can buy and possess them, but you may be replacing them often.
California has deemed large-capacity magazines to be a nuisance. See Cal. Pen. Code § 32390. That designation is dubious. The Supreme Court recognized a decade before Heller, “[g]uns in general are not ‘deleterious devices or products or obnoxious waste materials.’” Staples v. United States, 511 U.S. 600, 610 (1994) (citation omitted). Casting a common sized firearm magazine able to hold more than 10 rounds as a nuisance, as a way around the Second Amendment, is like banning a book as a nuisance, as a way around the First Amendment. It conjures up images from Ray Bradbury’s novel, Fahrenheit 451, of firemen setting books on fire, or in this case policemen setting magazines on fire. Plaintiffs remonstrate that the law’s forced, uncompensated, physical dispossession of magazines holding more than 10 rounds as an exercise of its “police power” cannot be defended. Supreme Court precedent casts doubt on the State’s contrary theory that an exercise of the police power can never constitute a physical taking. In Loretto, the Supreme Court held that a law requiring physical occupation of private property was both “within the State’s police power” and an unconstitutional physical taking. Loretto v. Teleprompter Manhattan CATV Corp., 458 U.S. 419 (1982). The Court explained that whether a law amounts to a physical taking is “a separate question” from whether the state has the police power to enact the law. Id. at 425–26 (“It is a separate question, however, whether an otherwise valid regulation so frustrates property rights that compensation must be paid. We conclude that a permanent physical occupation authorized by government is a taking without regard to the public interests that it may serve.”). In a similar vein, the Supreme Court holds that a law enacted pursuant to the state’s “police powers to enjoin a property owner from activities akin to public nuisances” is not immune from scrutiny under the regulatory takings doctrine. Lucas v. South Carolina Coastal Council, 505 U.S. 1003, 1020–27 (1992). The Court reasoned that it was true “[a] fortiori” that the “legislature’s recitation of a noxious-use justification cannot be the basis for departing from our categorical rule that total regulatory takings must be compensated.” Id. at 1026.