I thought you had the right to protect your livestock! Second they are not an endangered species. So to all who posted its illegal are you 150% sure you cant remove it if you catch it with your dead live stock. I want to here from someone who as had a personal experience with getting fined for killing a hawk, (not you've heard or know someone who has). If so please share your story. Thanks
Rather than depending on us then, why dont' you call fish and game and ask them about the regulations. Then you will have the facts in your area and know the consequences.
There are more responsible ways in this instance to protect your flock than killing. Hawks are an inconvenience you will need to learn to live with and protect your flock with other measures like overhead covers. If you decide to free range them, you need to provide them with multiple shelters to hide under and put up as much overhead cover as you can. string wire/or fish line, hang CDs, etc.
Some people have had good luck with crow decoys as well. It helps bring in other crows and the crows run off the hawks.
And finally, if you free range, you will occassionally lose chickens. It is a trade off.