I'm in the UK and have four indoor cats, its still frowned upon by a lot of people here including some of our vets but it's tough luck because my cats are staying inside! I do have a couple of harnesses but don't use them that often, next door's kids are usually out and are really noisy which scares my cats. When we buy our own house I'm going to have some sort of enclosure for them to go outside safely, I've already been looking into it and can't wait!