Ugh. Major fail on BOTH their parts.
First off, the truck is *already changing lanes* before the cop tries to pass him on the right. This is a stunt that MANY "4-wheelers" try to pull - Signal goes on, truck starts to move over, car jumps into the lane (or accelerates until they're next to the truck) to try to prevent the truck from getting in front of them. Note to non-idiots everywhere: Don't do this. It's a great way to get killed.
Second - The truck driver was not using his turn signal during the lane change. The trailer's rear turn signal never comes on. The trailer side turn signal never noticeably comes on, but that could be partially due to the lighting and angles involved... But while the tractor's rear turn signal is obscured by the lower-third TV graphics, on this Kenworth T600 there is a turn signal on the back of the fender behind the steer tire, just in front of the upper step that is clearly visible in the latter part of the crash and does not turn on.
Third - The truck doesn't stop. I know full well that it's possible to hit some pretty big things in a truck without noticing it, but I don't think that's the case here. The cop realizes at the last minute that he's not going to make it and hits the brakes. This prevents any part of the tractor from hitting him, but that means that the truck can continue to move over basically unencumbered - The trailer will begin crushing the top part of the car to the right, and the trailer tires will hit the left rear corner of the car. (Nick - Are you sure it was the *front* end of the car that was messed up? Got pictures?) You're gonna feel that.
Fourth - That cop is REALLY lucky to be alive. If he'd have hit is brakes just a fraction of a second later, the trailer would have made it far enough over that the tires would have gone UP instead of to the side, and let me tell ya what, when that happens, Bad Stuff happens to the car - It's not designed to hold up what will most likely be at least a 17,000-pound loading on that set of tires. I've watched it happen, though in the accident I saw the trailer's left side hit the car's right side (and it was the car's fault in that one too) - And the roof of the car on the right side was crushed right down to the passenger seat. Had there been a passenger, they'd have been dead no question, completely crushed. Luckily, there wasn't.
So, the truck driver should get cited for changing lanes without a signal and for leaving the scene of an accident - And since there were injuries, that is likely to mean jail time.
The cop, OTOH, should get cited for improper passing (immunity be damned), should get canned, and should thank his lucky stars he's still around to get canned. I hope he never pulls such an IDIOT move again in any vehicle.