I have confirmed that for the 2011 law school ranking, US News incorporated the opinions of 646 voters in determining overall law school reputation. (Additional voters were involved in the specialized rankings.) That 646 number includes both academics (who contribute to the academic reputation ranking - which is 25% of a school's overall score) and lawyers/judges (whose opinions make up 15% of a school's overall score.) Working backwards from the known response rate (65% for academics and 21% for lawyers and judges), it appears that about 520 of the voters are academics and 126 are lawyers and judges.
One question I've been pondering is: how many of those surveyed don't bother to rate dozens of law schools? I wouldn't be surprised if many people skip over schools they don't know. That would mean that many schools are being ranked on far, far fewer than 646 responses.
Meanwhile, one law school is apparently trying to understand what those 520 law school voters are thinking about when they assess a school's reputation. I've been forwarded an email sent by the Hanover Research group stating that they've been retained by Wayne State to conduct a 10-15 minute "survey of law professionals concerning the factors they consider to be important in determining law school quality and reputation." A survey of the surveyed!
I'm not going to lie. I consider delicious salsa a highly compelling factor!