From the factory, there is an emergency trunk release in the trunk. It should have a glow-in-the-dark T handle, unless someone removed it, and it should be hanging from the inside of the trunk lid. It is true that it's a cable-pull, not a lever, though, so someone may have clipped the cable, or it may have gotten stuck behind the interior trim.
I don't remember if it's Federally-mandated, but it's standard equipment on all cars with trunks, and has been for a decade or so. It's included as a safety feature, to prevent people from being trapped inside the trunk. (That's also why the handle is glow-in-the-dark.)