There are several breeds of working, shepherding dogs that can and will kill wolves.
Caucasian Mountain Dog.
Great Pyrenees Dog
Kangal Dog
Sarplaninac Dog
If you are talking about a wolf pack against a single dog, the dog loses, if you are talking one on one or pack against pack the dogs are just as good as the wolves.
None of which should be necessary. Nor will it avoid prosecution for killing a protected wolf.
Great Pyrenees Dogs are used around here to protect sheep, mostly from coyotes. From time to time they take out a lion. Sometimes the lions win but not as often as two dogs on the lion.
How about a breed of dog specifically bred to chase down and kill wolves? An Irish Wolfhound might be a gentle giant with people and other dogs but it will go absolutely berserk when it sees a wolf or coyote. They have a fighting style perfect for a wolf which will inevitably go low. The wolfhound will use its height to grab the back of the wolf's neck, a quick twist of the wolfhound's head and the fight is over.
A single Irish wolfhound isn't going to kill a pack of wolves but a pack of wolfhounds can eliminate a larger pack of wolves.
Excellent advice. Here is an article that explains the various breeds as well:
http://www.wolvesandhumans.org/articles/protecting_livestock_from_large_carnivores.htm