I have to disagree with you guys.
I know that law schools look at UGPA and LSAT score with the most weight, however, I think that the masters degree does make a difference depending on the person, what they are doing, how long they have been out of school, and what they intend to do in law school and what they want to do when they get out of law school.
I think that having a masters degree can not hurt, unless you have a low GPA. But for someone who gets a masters and has a high GPA, the masters degree is another thing to separate them from the people who do not have them. I think in certain situations they can help a person when it comes down to a few people with round about the same credentials.
I think that my masters degree will help me be able to be more specific for what I want out of law school and what I want in the long run. For example, I have a strong UGPA, an ok LSAT score… I took it again and will get the scores on July 6th (pretty confident I went up the 10 points that make most schools ignore my lower LSAT). I want to work in media law, I am working full time as a marketing manager, and I am getting my masters full time at night, will be done in May, so far the GPA is a 4.0. My masters is in public and corporate communications (deals a lot with media, persuasion, advertising, communication, ethics, and so on), this degree can only help me explain why I want to go into media law, what I have already done to become knowledgeable in the field, and what I would like to get out of law school. It will definitely separate me from some of the people who have a good UGPA and a similar LSAT score.
I am only 22, but I would bet someone who has been out of school for a long time and has recently got a masters degree can show that they can still excel in school. People who might have done poorly in Under Grad and 5 years later do phenomenal in grad school can write an addendum to make the claim that they grew up and focused.
I am not saying that the masters degree will get you accepted to Columbia, but I think overall, it makes a difference depending on how you use it to sell yourself to a school. No education is useless, especially when applying to law school. Every little thing separates you from the person next to you.