It is legal to own a wolf or wolf hybrid as long as you are NOT breaking any laws, be they Local, State or Federal. Federal Law covers pure wolves. Unites States Department of Agriculture (USDA) covers the ownership of pure wolves. Education of ones self regarding the ownership of one of these animals regarding the legality within your area is a MUST and will save you much undo heartache and possible expense. Information is available within the Internet regarding any aspect of wolves and wolf hybrids. Keyword wolves +hybrids will start you on your way. Welcome to the community of wolf and wolf hybrid interaction, not really ownership.
For more information on state-by-state regulations and updates, visit:
National Wolf dog Alliance (NWA)'s Legislative Updates: Current State Laws and Related Links
Wildlife Education & Research Foundation (WERF)'s State Regulations Pertaining to Wolves and Wolf Hybrids.
Keep in mind that even if your state says more recent wolf x dog crosses are regarded as dogs (and are subject to dog licensing, etc.), your county or town may have restrictions or bans on the books regarding wolf "hybrids".
You need to go to the above web site and check the particular state you are interested in.