Call a Fish and Game warden.. that'll answer your legality question right there. Otherwise.. do you have a dog? Perferably a herding or livestock guardian breed? My border collie loathes any wild things in our yard, but she's been trained not to touch the chickens. So far, she's run off 3 hawks that came calling. She even stopped one mid-stoop.
My little silkie was foraging in the middle of the yard, away from cover. Suddenly, I heard an alarm squawk from my arucana hen, and looked up to see a hawk mid-dive, aimed for my silkie, who only looked around in confusion when I screamed her name. I swear, Diamond (my border collie) was standing beside me one moment, and the next moment she was in front of the silkie, legs braced and mouth open, ready to catch the hawk. It was hilarious to see the hawk frantically aborting its dive and flying up again.. Diamond then proceeded to run around the yard, barking at the hawk and daring it to try again.
That was the closest one thus far, the next closest was one that hovered about 50 feet above the yard, again, she ran around barking her head off at it and staying right under it while the chickens ran for the bushes (they use the Boxwoods and Knockout Roses for shelter).