I imagine it is taken into account depending on the circumstances. Some people face major setbacks if they disclose their sexuality to their parents or their family discovers it regardless; that can mean being kicked out of their house, having their entire future disrupted, etc. On the other hand, some people (and I include myself in this category) have a relatively easy time of it, their parents are understanding and it does not set them back (at least not financially). That being said, I think it allows applicants to weed out law schools just as it allows law schools to find sexual minorities. I'm pretty certain that by checking on the box I avoided mail from a lot of Catholic, conservative and Protestant schools (save Notre Dame, which sent me a packet with a two page explanation of why they were not including "sexual orientation" in their nondiscrimination policy). All the better.