TMZ has a nifty little video of Nick grabbing a member of paparazzi around the throat and threatening bodily harm. Of coarse, Nick's people claim otherwise.
It seems as though the photog said something mean and uncalled for to girlfriend Vanessa Minnillo. That seems totally believable to me. It was probably some cringe worthy yet hysterical comment about Nessa playing knife games with different troubled actresses. I think that would be something to provoke Nick who is obviously quite chivalrous.
Both parties claim the other is totally at fault. Chances are the photographer struck a low blow at Vanessa and Nick snapped. It's not easy when sexy pics of your girlfriend brandishing a sharp object surface.