Hi there
I let Callie out in our backyard without a leash, it is fenced in, but I never leave her out there, she's still too tiny (2.2# as of Thurs), she chases birds but thankfully not rabbits or squirrels. Plus, the dogs that live behind us are rat terriers and scare the crap out of me, I think that if one were to get enough adrenalin to jump over the fence she would hurt Callie, they always bark like CRAZY at her and Callie thinks she can take them (puffs up her chest and barks back).
I let her out in the front yard with me when I get the mail, water flowers, pull weeds, etc. but always keep her in close view. She LOVES people (runs over to strangers like 'yay! friend!!') so I only do this leashless before 5pm when neighbors get home from work.
Otherwise, it is the law here to have your dog on a leash. Callie would LOVE to not be leashed, but I don't want to get a citation!!