The one which defines the "breakdown lane". If you are not in need of assistance you should not be driving in the breakdown lane. It is also called the emergency lane.
Squid -- you need to take a breath and SLOW DOWN. Getting into fisticuffs with a trucker?!? That's not Prius behavior! I'm the guy that takes it easy and follows the law. I stay in the right lane until I get to my exit, then I exit. You're the a-hole who zooms up in the emergency lane and cuts me off when it's MY turn to get off the highway at the exit. But I just smile and let you by. I know you'll get sideswiped or worse if you keep it up. It's road karma, dude. Chill!