Can there be dominance without agression? No - it is like smoke without fire... it is the communicated threat of aggression which provide the non contact dominance.

I have to disagree to a large extent with this statement Gary. Some of displays of aggression may be breed dependent protective behavior which may or may not be dominant behavior such as with some LGDs or it may not have anything to do with dominance at all. What appears to be aggressive dominant behavior can be something as simple as a dog acting out because he is frustrated at his owner because the owner cannot read the dog or communicate properly to the dog to let it know what he wants it to do.

Aggressive behavior can be from some form of anxiety that the dog has because it wants to avoid some aversive outcome based on previous bad experiences. For example, compulsive punitive training methods. From my experience, the most dominant dogs of all are the ones that are most confident and also the most benevolent. They outwardly physically display that confidence in the way they carry themselves. They only display aggressive behavior and use force only when absolutely necessary. When possible they are the ones that will mostly ignore outward displays of aggression from other dogs. They will allow puppies and other dogs to come and take a bone from them. They don't react in most situations because they know what they are capable of doing and just really don't care. They are dogs that will feed of off their owners emotions and will be largely indifferent to their surroundings if their owners are.

They are dogs that when they are around their human family will quietly and unnoticeably place themselves by the youngest and meekest human member of their family. This can be from something as simple as sleeping in the granddaughter's room when she comes to visit to calmly placing itself between a family member and a potential threat as noted by Esprinter's example. And as Mike noted it can also be something as simple as the dog coming up to you after you stopped petting it, and putting its head under your hand and nudging you, MAKING you pet them. Not all aggression has to be hair up, teeth baring and all that jazz.

But a dog demonstrating that behavior can also be doing that purely because he likes it and has learned and ultimately trained his owner to pet him merely by nudging his hand and not have anything to do with being dominant at all. I could get into the similar related arguments about the endless list of human dog pack dominance rules about pulling on the lead, walking through the door first, eating first, getting on the bed or furniture etc but that is getting off topic.

Anyway the moral of my long winded but not quite Wolfbytean epistle is that we have to be careful when talking about dominance and aggressive behavior because in many cases they are not the same thing or even related behaviors.

Lastly, I also have to note that this is just my opinion based on my experiences.