I heard the same thing from a couple of my schools too. There is a possibility they will be going to the waiting list, but each day that passes that chance is less likely. Most students have had to pay some, if not all, of their fall tuition by now, so many are reluctant to jump ship after putting down the big bucks. However, there are a few people out there who may have just gotten into a higher tier and feel it is an opportunity they cannot turn down, or may decide for personal reasons that law school isnt going to work out. In that case, you may be offered a seat. However, these chances are small, so I wouldnt risk a seat at your present law school holding your breath for the waiting list. Most schools start in less than a month, so anyone that would be taken from the waiting list would be by a case-by-case wait list (not like the larger amount of offers that are usually made after the first & second seat deposit deadlines to schools). at best, I would say hold out until the beginning of august, but after that you really should focusing on the school to which youve been accepted. I know it sucks to hear that, but you could always transfer.
Basically, the over-enrollment is often a consequence of the admissions selection a law school uses in its decision-making process. Based on their previous numbers, law schools that tend to "over-enroll" send out a more generous amount of acceptances within their LSAT/GPA range, knowing that many of those students will accept their offer. As a result, these schools fill their class from the get-go, and do not have to trouble themselves much by returning to select applicants from the waiting lists. Other schools, however, use different approaches. Some, to maintain highly selective ranking numbers, only send out a "small" amount of admissions letters to those students they really liked. Those same schools tend to have a smaller but strong waiting list of candidates of which they were also impressed but who do not have the highest scores to boost their school's rankings. If their class does not fill from the initial offers, they continue to make their class highly selective by re-evaluating all of their waiting list candidates in effort to flesh out their incoming class (ie who has the next highest scores, what geographic region do they need more people from, what gender/nationality do they need more of, etc etc). The admissions process is such a game, its hard to anticipate your chances.
Also, I'm not sure which schools you're talking about, but check out this website. http://www.lawschoolpower.com/Law_School_Waitlist_Data.htm
It lists the % of applicants a school waitlists and how many are usually taken from the waiting list. Maybe you could form a better idea of whether or not your school is a very active waitlist school or not.
If you are still very interested in your waiting list schools and are willing to wait until the last minute, I would repeatedly send them emails. You do not want to get annoying, but I would send a letter of continued interest every week or so, so that your name repeatedly is at the top of their inbox and they remember you when they turn to the waiting list. I would also visit the school if you can and request to speak to an admissions counselor, where you should express your sincere interest to attend the school. If possible, secure an extra letter of recommendation.
Good luck, I hope it works out for you!