Tell them to go back to Mexico, or wherever they came from.
25% of California is foreign born.
Our federal system was originally set up to be a union of sovereign states allowing for differences between each one. The real solution to their problem is states rights. When the majority of important decisions are made at the level of the central government states have less control over their own lives.
Being smug about forcing your onions on others diminishes the validity of your objection when it comes back your way.
What comes around goes around.