How does a switchblade retract?

To retract the blade the button is again pressed so that its slot aligns with the blade. The cocking arm is pulled backwards which itself pulls the blade backward. When the blade is fully retracted the spring mounted button rests in the forward notch and again pops up and locks the blade in the cocked position.

Is a switch knife illegal?

A switchblade (which may be known by many other names including a “pushbutton knife” or “ejector knife”) has a blade which is contained within the handle and is opened automatically by a spring by pushing a button or switch on the handle. Switchblades with blades longer than 2” are illegal to carry in California.