The doctrine known as assumption of the risk, is a legal construct, established in the common (i.e.., court-made) law which says, in essence, that someone who is injured in an activity that is inherently dangerous can't claim damages from being injured during that activity. So, for example, if you're beaned by a foul ball that hits you while you're a spectator at a baseball game, you're SOL (another legal construct, loosely translated as sadly out of luck) as far as being able to sue anyone for your injuries. Similarly, if you've served honorably in the armed forces and decide to run for public office against a Republican opponent, you're not going to be able to complain when s/he questions your service and suggests you were actually a coward, because being Swift-boated is just a risk you assume when you take on a Republican opponent.
There are many other things we do where we assume the risk of something bad happening. Running with the bulls in Pamplona, riding one of those crotch rocket motorcycles down a city street at 100 plus miles per hour, and jumping out of an airplane from 20,000 feet with nothing more than a few yards of silk to slow your fall all come immediately to mind. But there are some consequences of potentially risky activities we all undertake which we definitely do not assume the risk of. Food preparation, electricity and driving all involve elements of risk, but none of us assumes the risk of contracting salmonella from eating in a restaurant, being electrocuted by our computers or being run into by an 18-wheeler on the road. When any of those things happen, it's not because of a risk we assumed, it's because someone screwed up royally, which is what Mr. Cheney did when he shot Mr. Whittington.
In bending over backwards (or maybe forward) to kowtow to the Vice President, Mr. Whittington would have us believe that hunters assume the risk of being shot. Yes, hunting entails a certain amount of danger, if for no other reason than that lethal weapons are involved, but a steak knife is a lethal weapon, yet no one assumes the risk that they'll be stabbed by one while having a steak dinner with friends. The worst a hunter anticipates is wetting himself because the zipper on his hunting garment jammed at an inopportune moment. Strangely enough, statistics show that fewer people are injured in hunting accidents than in dozens of other activities, from taking a bath to playing golf.
Now maybe it's a different matter if one of your hunting companions is taking a potent mix of pharmaceuticals to keep his heart from stopping, has a history of alcohol abuse, and is willing to admit he only had a beer shortly before he slung his shotgun over his shoulder. If being shot while hunting were as risky as Mr. Whittington would have us believe, then hunting attire would be made with kevlar (which it isn't), and hunters wouldn't be able to get life insurance (which they can). No, the only risk Mr. Whittington assumed by hunting with Dick Cheney was that if he was shot, someone would try to blame him for it.