The conventional answer argued by the government's lawyers is that federal law trumps the right declared by the people's vote and that's that. Oakland's brief argues that the people have reserved the power to enact popular initiatives. When the people pass an initiative protecting a particular liberty, judges should respect this unenumerated liberty as they would an enumerated right. In other words, the initiative process enables the voters of each state to decide themselves if a liberty is fundamental, rather than leave that decision solely to judges. When deciding whether such a liberty is fundamental, federal judges are required by an appropriate judicial conservatism to respect the people's judgment.
Government can still restrict marijuana use.
The simple answer is yes, though it is hard to imagine a successful initiative on behalf of child pornography. Courts have, with rare exception, been reluctant to use the Ninth Amendment in large measure for fear of opening a Pandora's box of alleged rights. This judicial neglect of the Ninth Amendment could end, however, if the Ninth Circuit simply recognizes the people's initiative power to designate fundamental liberties, thereby shifting the burden of proof onto the federal government to show that restrictions on liberty are both necessary and proper.